fix metadata - author (dotnet#9831)

Author: mairaw

aspnetcore/tutorials/first-mongo-app.md

@@ -1,6 +1,6 @@
 ---
 title: Build web APIs with ASP.NET Core and MongoDB
-author: pratik-khandelwal
+author: prkhandelwal
 description: This tutorial demonstrates how to build an ASP.NET Core web API using a MongoDB NoSQL database.
 ms.author: scaddie
 ms.custom: mvc