DOC: Add default path for screenshots

The information used to be in the README file but was removed when
the doc portal was introduced. However that information was never
added to the doc portal. I am not sure where the best place was to
add this information. I considered using the Settings/Paths page,
but since the screenshot page is not exposed in the Options dialog
this did not seem to be the right place. So in the end I added it
on the Configuration file page, with a link from the Keyboard
shortcuts page.

doc/docportal/advanced_topics/configuration_file.rst

@@ -391,7 +391,7 @@ There are many recognized configuration keys. In the table below, each key is ei
 		save_slot,integer,autosave, Specifies the saved game slot to load
 		":ref:`scalemakingofvideos <scale>`",boolean,false,
 		":ref:`scanlines <scan>`",boolean,false,
-		screenshotpath,string,,Specifies where screenshots are saved
+		screenshotpath,string,See :ref:`screenshotpath <screenshotpath>`,Specifies where screenshots are saved
 		sfx_mute,boolean,false, Mutes the game sound effects.
 		":ref:`sfx_volume <sfx>`",integer,192,
 		":ref:`shorty <shorty>`",boolean,false,
@@ -430,13 +430,40 @@ There are many recognized configuration keys. In the table below, each key is ei
 
 
 
+.. _screenshotpath:
 
+Screenshot path
+	The default location for the screenshotpath depends on your system.
 
 
+	.. tabbed:: Windows
 
+		.. panels::
+			:column: col-lg-12 mb-2
 
+			In ``Users\username\My Pictures\ScummVM Screenshots``
 
+	.. tabbed:: macOS
 
+		.. panels::
+			:column: col-lg-12 mb-2
+
+			On the Desktop.
+
+
+	.. tabbed:: Linux
+
+		.. panels::
+			:column: col-lg-12 mb-2
+
+			In the XDG Pictures user directory, for example ``~/Pictures/ScummVM Screenshots``
+
+	.. tabbed:: Any other OS
+
+		.. panels::
+			:column: col-lg-12 mb-2
+
+			In the current directory.
 
 
 

doc/docportal/use_scummvm/keyboard_shortcuts.rst

@@ -27,5 +27,5 @@ Default shortcuts are shown in the table.
         :kbd:`Ctrl+Alt+f` ,Toggles between nearest neighbor and bilinear interpolation (graphics filtering on/off)
         :kbd:`Ctrl+Alt+s` ,Cycles through stretch modes
         :kbd:`Alt+Enter` ,Toggles full screen/windowed mode
-        :kbd:`Alt+s` ,Takes a screenshot
+        :kbd:`Alt+s` ,Takes a :ref:`screenshot <screenshotpath>`
         :kbd:`Ctrl+F7`,"Opens virtual keyboard (if enabled). This can also be opened with a long press of the middle mouse button or wheel."