Update the sample code to match the actual code (microsoft#1709)

<!--- Provide a general summary of your changes in the Title above -->

## Description
<!--- Describe your changes in detail -->
This PR updates the sample code on the `TeachingTip` page to match the
actual code.

## Motivation and Context
<!--- Why is this change required? What problem does it solve? -->
<!--- If it fixes an open issue, please link to the issue here. -->
The current sample code doesn't match the actual code and doesn't even
compile.

## How Has This Been Tested?
<!--- Please describe in detail how you tested your changes. -->
<!--- Include details of your testing environment, and the tests you ran
to -->
<!--- see how your change affects other areas of the code, etc. -->
Ran the app and confirmed its contents.

## Screenshots (if appropriate):

## Types of changes
<!--- What types of changes does your code introduce? Put an `x` in all
the boxes that apply: -->
- [x] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)

WinUIGallery/ControlPages/TeachingTipPage.xaml

@@ -20,19 +20,19 @@
     <StackPanel HorizontalAlignment="Left">
         <local:ControlExample
             CSharpSource="TeachingTip/TeachingTipSample1_cs.txt"
-            HeaderText="Show a targeted TeachingTip on the Toggle Theme button."
+            HeaderText="Show a targeted TeachingTip on a button."
             XamlSource="TeachingTip/TeachingTipSample1_xaml.txt">
             <local:ControlExample.Example>
                 <Grid>
                     <Button
-                        x:Name="ThemeButton"
-                        Click="TestButtonClick1"
+                        x:Name="TestButton1"
+                        Click="TestButton1Click"
                         Content="Show TeachingTip" />
                     <TeachingTip
-                        x:Name="ToggleThemeTeachingTip1"
+                        x:Name="TestButton1TeachingTip"
                         Title="This is the title"
                         Subtitle="And this is the subtitle"
-                        Target="{x:Bind ThemeButton}">
+                        Target="{x:Bind TestButton1}">
                         <TeachingTip.IconSource>
                             <SymbolIconSource Symbol="Refresh" />
                         </TeachingTip.IconSource>
@@ -47,9 +47,11 @@
             XamlSource="TeachingTip/TeachingTipSample2_xaml.txt">
             <local:ControlExample.Example>
                 <Grid>
-                    <Button Click="TestButtonClick2" Content="Show TeachingTip" />
+                    <Button
+                        Click="TestButton2Click"
+                        Content="Show TeachingTip" />
                     <TeachingTip
-                        x:Name="ToggleThemeTeachingTip2"
+                        x:Name="TestButton2TeachingTip"
                         Title="This is the title"
                         ActionButtonContent="Action button"
                         CloseButtonContent="Close button"
@@ -63,22 +65,24 @@
 
         <local:ControlExample
             CSharpSource="TeachingTip/TeachingTipSample3_cs.txt"
-            HeaderText="Show a targeted TeachingTip with hero content on the Toggle Theme button."
+            HeaderText="Show a targeted TeachingTip with hero content on a button."
             XamlSource="TeachingTip/TeachingTipSample3_xaml.txt">
             <local:ControlExample.Example>
                 <Grid>
                     <Button
-                        x:Name="HeroButton"
-                        Click="TestButtonClick3"
+                        x:Name="TestButton3"
+                        Click="TestButton3Click"
                         Content="Show TeachingTip" />
                     <TeachingTip
-                        x:Name="ToggleThemeTeachingTip3"
+                        x:Name="TestButton3TeachingTip"
                         Title="This is the title"
                         PreferredPlacement="Bottom"
                         Subtitle="And this is the subtitle"
-                        Target="{x:Bind HeroButton}">
+                        Target="{x:Bind TestButton3}">
                         <TeachingTip.HeroContent>
-                            <Image AutomationProperties.Name="Sunset" Source="/Assets/SampleMedia/sunset.jpg" />
+                            <Image
+                                AutomationProperties.Name="Sunset"
+                                Source="/Assets/SampleMedia/sunset.jpg" />
                         </TeachingTip.HeroContent>
                         <TeachingTip.Content>
                             <TextBlock

WinUIGallery/ControlPages/TeachingTipPage.xaml.cs

@@ -20,19 +20,19 @@ public TeachingTipPage()
             this.InitializeComponent();
         }
 
-        private void TestButtonClick1(object sender, RoutedEventArgs e)
+        private void TestButton1Click(object sender, RoutedEventArgs e)
         {
-            ToggleThemeTeachingTip1.IsOpen = true;
+            TestButton1TeachingTip.IsOpen = true;
         }
 
-        private void TestButtonClick2(object sender, RoutedEventArgs e)
+        private void TestButton2Click(object sender, RoutedEventArgs e)
         {
-            ToggleThemeTeachingTip2.IsOpen = true;
+            TestButton2TeachingTip.IsOpen = true;
         }
 
-        private void TestButtonClick3(object sender, RoutedEventArgs e)
+        private void TestButton3Click(object sender, RoutedEventArgs e)
         {
-            ToggleThemeTeachingTip3.IsOpen = true;
+            TestButton3TeachingTip.IsOpen = true;
         }
     }
 }

WinUIGallery/ControlPagesSampleCode/TeachingTip/TeachingTipSample1_xaml.txt

@@ -1,9 +1,12 @@
-<Button Content="Show TeachingTip" Click="TestButtonClick1" />
-
-<TeachingTip x:Name="ToggleThemeTeachingTip1"
-    Target="{x:Bind ThemeButton}"
-    Title="Change themes without hassle"
-    Subtitle="It's easier than ever to see control samples in both light and dark theme!">
+<Button
+    x:Name="TestButton1"
+    Click="TestButton1Click"
+    Content="Show TeachingTip" />
+<TeachingTip
+    x:Name="TestButton1TeachingTip"
+    Title="This is the title"
+    Subtitle="And this is the subtitle"
+    Target="{x:Bind TestButton1}">
     <TeachingTip.IconSource>
         <SymbolIconSource Symbol="Refresh" />
     </TeachingTip.IconSource>

WinUIGallery/ControlPagesSampleCode/TeachingTip/TeachingTipSample2_xaml.txt

@@ -1,12 +1,12 @@
-<Button Content="Show TeachingTip" Click="TestButtonClick2" />
-
-<TeachingTip x:Name="ToggleThemeTeachingTip2"                   
-	Title="Change themes without hassle"
-	Subtitle="It's easier than ever to see control samples in both light and dark theme!"
-	PreferredPlacement="Auto"                                              
-	PlacementMargin="20"
-	IsLightDismissEnabled="True"
-	ActionButtonClick="ToggleThemeTeachingTip2_ActionButtonClick"
-	ActionButtonContent="Toggle theme now"
-	CloseButtonContent="Got it!">
-</TeachingTip>
+<Button
+    Click="TestButton2Click"
+    Content="Show TeachingTip" />
+<TeachingTip
+    x:Name="TestButton2TeachingTip"
+    Title="This is the title"
+    ActionButtonContent="Action button"
+    CloseButtonContent="Close button"
+    IsLightDismissEnabled="True"
+    PlacementMargin="20"
+    PreferredPlacement="Auto"
+    Subtitle="And this is the subtitle" />

WinUIGallery/ControlPagesSampleCode/TeachingTip/TeachingTipSample3_xaml.txt

@@ -1,14 +1,22 @@
-<Button Content="Show TeachingTip" Click="TestButtonClick3" />
-
-<TeachingTip x:Name="ToggleThemeTeachingTip3" 
-    Target="{x:Bind ThemeButton}"
-    Title="Change themes without hassle"
-    Subtitle="It's easier than ever to see control samples in both light and dark theme!"
-    PreferredPlacement="LeftEdgeAlignedBottom">
+<Button
+    x:Name="TestButton3"
+    Click="TestButton3Click"
+    Content="Show TeachingTip" />
+<TeachingTip
+    x:Name="TestButton3TeachingTip"
+    Title="This is the title"
+    PreferredPlacement="Bottom"
+    Subtitle="And this is the subtitle"
+    Target="{x:Bind TestButton3}">
     <TeachingTip.HeroContent>
-        <Image Source="/Assets/SampleMedia/sunset.jpg" AutomationProperties.Name="Sunset" />
+        <Image
+            AutomationProperties.Name="Sunset"
+            Source="/Assets/SampleMedia/sunset.jpg" />
     </TeachingTip.HeroContent>
     <TeachingTip.Content>
-        <TextBlock TextWrapping="WrapWholeWords" Margin="0,16,0,0">To change your desktop theme visit the <Hyperlink NavigateUri="ms-settings:colors">Settings app</Hyperlink>.</TextBlock>
+        <TextBlock
+            Margin="0,16,0,0"
+            Text="Description can go here"
+            TextWrapping="WrapWholeWords" />
     </TeachingTip.Content>
 </TeachingTip>