chore: add language identifiers

src/content/docs/apm/agents/net-agent/troubleshooting/missing-net-async-metrics.mdx

@@ -43,7 +43,7 @@ To use the upgraded pipeline, ensure your `web.config` includes one of the follo
   >
     Tell .NET to use the new ASP request processing pipeline:
 
-    ```
+    ```xml
     <configuration>
       <appSettings>
         <add key="aspnet:UseTaskFriendlySynchronizationContext" value="true" />
@@ -60,7 +60,7 @@ To use the upgraded pipeline, ensure your `web.config` includes one of the follo
 
     The specified version of the .NET Framework must be installed on your machine, and it must be version 4.5.2 or higher:
 
-    ```
+    ```xml
     <configuration>
       <system.web>
         <httpRuntime targetFramework="YOUR_TARGET_NET_VERSION" /> 
@@ -78,7 +78,7 @@ If your app passes without any issues, you can be confident that your app correc
 
 To enforce additional checks, add the following to `web.config`:
 
-```
+```xml
 <configuration>
   <appSettings>
     <add key="aspnet:AllowAsyncDuringSyncStages" value="false" />
@@ -90,5 +90,5 @@ To enforce additional checks, add the following to `web.config`:
 
 Async instrumentation is disabled if the legacy integrated pipeline is present. Before .NET 4.5, the integrated pipeline could cause deadlocks. For more information about this .NET Framework bug, see:
 
-* [Why is HttpContext.Current null after await?](http://stackoverflow.com/questions/18383923/why-is-httpcontext-current-null-after-await)
+* [Why is `HttpContext.Current` null after await?](http://stackoverflow.com/questions/18383923/why-is-httpcontext-current-null-after-await)
 * [All about &lt;httpRuntime targetFramework>](http://blogs.msdn.com/b/webdev/archive/2012/11/19/all-about-httpruntime-targetframework.aspx)