Add instructions for viewing build-time OpenAPI logs with Terminal Logger

Author: mohaimenpxl

src/Tools/Extensions.ApiDescription.Server/README.md

@@ -6,3 +6,17 @@ MSBuild glue for OpenAPI document generation.
 
 See partner packages such as [NSwag.AspNetCore](https://www.nuget.org/packages/NSwag.AspNetCore/) or
 [Swashbuckle.AspNetCore](https://www.nuget.org/packages/Swashbuckle.AspNetCore/) for intended use.
+
+## Viewing build-time OpenAPI logs (Terminal Logger)
+
+When `Microsoft.Extensions.ApiDescription.Server` runs the **GetDocument** step during `dotnet build`, its progress messages may not appear with the .NET **Terminal Logger** at default verbosity (the default in .NET 8+).  
+To surface these messages while building:
+
+
+```powershell
+dotnet build -tlp:v=d   # Detailed terminal logger verbosity
+# or
+dotnet build --tl:off   # Disable terminal logger and use legacy-style logs
+```
+
+This will display messages like Generating document named 'v1' which are hidden at normal verbosity and can be useful for diagnosing document generation issues.