Add PMC instructions (#69)

Author: AndriySvyryd

docs/2. Build out BackEnd and Refactor.md

@@ -420,6 +420,15 @@ Okay, now we need to update our `ApplicationDbContext` so Entity Framework knows
 1. Ensure that the application builds now.
 
 ## Add a new database migration
+
+### Visual Studio: Package Manager Console 
+1. Run the following commands in the Package Manager Console
+   ```console
+   Add-Migration Refactor
+   Update-Database
+   ```
+
+### Command line
 1. Run the following commands in the command prompt in the `BackEnd` project directory:
    ```console
    dotnet ef migrations add Refactor