Clarify example of IsTargetFrameworkCompatible

The examples for IsTargetFrameworkCompatible give two examples of incompatible TFMs, but don't give any examples of compatible TFMs, so it isn't super clear how to use the API. Added a "Value8" example that shows that `net6.0` is compatible with `net8.0`.

Author: MattKotsenas

docs/msbuild/property-functions.md

@@ -596,6 +596,7 @@ The following example shows how these functions are used.
         <Value5>$([MSBuild]::IsTargetFrameworkCompatible('net5.0-windows', 'net5.0'))</Value5>
         <Value6>$([MSBuild]::IsTargetFrameworkCompatible('net5.0', 'net6.0'))</Value6>
         <Value7>$([MSBuild]::IsTargetFrameworkCompatible('net5.0', 'net8.0'))</Value7>
+        <Value8>$([MSBuild]::IsTargetFrameworkCompatible('net8.0', 'net6.0'))</Value8>
     </PropertyGroup>
 
     <Target Name="MyTarget">
@@ -606,6 +607,7 @@ The following example shows how these functions are used.
         <Message Text="Value5 = $(Value5)" />
         <Message Text="Value6 = $(Value6)" />
         <Message Text="Value7 = $(Value7)" />
+        <Message Text="Value8 = $(Value8)" />
     </Target>
 </Project>
 ```
@@ -618,6 +620,7 @@ Value4 = 7.0
 Value5 = True
 Value6 = False
 Value7 = False
+Value8 = True
 ```
 
 ::: moniker range=">=vs-2022"