Sort the owners file alphabetically (istio#2658)

OWNERS

@@ -1,28 +1,29 @@
+# Please add your github ID alphabetically.
 reviewers:
-  - geeknoid
   - andraxylia
   - costinm
   - Douglas-reid
+  - frankbu
+  - geeknoid
+  - hklai
+  - kyessenov
   - ldemailly
+  - linsun
+  - mandarjog
   - rshriram
   - sebastienvas
-  - mandarjog
-  - frankbu
-  - linsun
-  - kyessenov
-  - hklai
   - wattli
 approvers:
-  - geeknoid
   - andraxylia
   - costinm
   - Douglas-reid
-  - ldemailly
-  - rshriram
-  - mandarjog
   - frankbu
-  - linsun
-  - kyessenov
+  - geeknoid
   - hklai
+  - kyessenov
+  - ldemailly
+  - linsun
+  - mandarjog
+  - rshriram
+  - sebastienvas
   - wattli
-