Update develop.md

Server port is incorrect, due this issue server cannot be available at http://localhost:8080/

Author: Bobbypip

content/guides/dotnet/develop.md

@@ -92,7 +92,7 @@ services:
       context: .
       target: final
     ports:
-      - 8080:80
+      - 8080:8080
     depends_on:
       db:
         condition: service_healthy