Fix language tags in doc-snippets

The doc-snippets were inconsistent
(no spaces before title, small-caps, JS
instead of JavaScript, etc.)

apps/tests/layouts/absolute-layout-tests.ts

@@ -14,7 +14,7 @@ import absoluteLayoutModule = require("ui/layouts/absolute-layout");
 // </snippet> 
 
 // ### Declaring a AbsoluteLayout.
-//```XML
+//``` XML
 // <Page>
 //   <AbsoluteLayout>
 //     <Label text="This is Label 1" left="30" top="70" />

apps/tests/layouts/dock-layout-tests.ts

@@ -14,7 +14,7 @@ import dockModule = require("ui/layouts/dock-layout");
 // ```
 
 // ### Declaring a DockLayout.
-//```XML
+//``` XML
 //<Page>
 //  <DockLayout stretchLastChild="true" >
 //    <Button dock="left" text="left" style="background-color: red; margin: 5;"/ >/ >

apps/tests/layouts/stack-layout-tests.ts

@@ -171,7 +171,7 @@ export class StackLayoutTest extends testModule.UITest<StackLayout> {
         //  ```
 
         // ### Declaring a StackLayout.
-        //```XML
+        //``` XML
         // <Page>
         //   <StackLayout orientation="horizontal">
         //     <Label text="This is Label 1" />

apps/tests/layouts/wrap-layout-tests.ts

@@ -28,7 +28,7 @@ export class WrapLayoutTest extends testModule.UITest<wrapLayoutModule.WrapLayou
         // </snippet>
 
         // ### Declaring a WrapLayout.
-        //```XML
+        //``` XML
         // <Page>
         //   <WrapLayout>
         //     <Label text="This is Label 1" />