Update 'Project Setup Guide Project: Serenity'

Project-Setup-Guide---Project%3A-Serenity.md

@@ -102,7 +102,7 @@ Once you've cloned the repo via SSH, you can manage it more easily using SourceT
 2. Click **"Add"** in the top menu.
 3. In the **Add Working Copy** tab:	
 	* **Working Copy Path:**
-    Browse to your cloned project folder (e.g., C:\Repositories\ProjectSerenity)
+    Browse to your cloned project folder (e.g., C:\Repositories\ProjectSerenity) - Once you've added the location, click in the empty space and wait for SourceTree to make sure it is a Git repo. If it says it is, continue.
     * **Repository Type:**
     Git (should be selected by default)
     * **Name:**