Remove .NET Core suffix from project-sdk folder (dotnet#20771)

Author: Youssef1313

docfx.json

@@ -573,7 +573,7 @@
         "docs/core/migration/**.md": ".NET Core",
         "docs/core/porting/**.md": ".NET Core",
         "docs/core/run-time-config/**.md": ".NET Core",
-        "docs/core/project-sdk/**.md": ".NET Core",
+        "docs/core/project-sdk/**.md": ".NET",
         "docs/core/testing/**.md": ".NET Core",
         "docs/core/tools/**.md": ".NET Core CLI",
         "docs/core/tutorials/**.md": ".NET Core",