Update and rename 2-what-is-github2.yml to 2-what-is-github.yml

Author: barneschism

learn-pr/github/introduction-to-github/2-what-is-github2.yml renamed to learn-pr/github/introduction-to-github/2-what-is-github.yml

@@ -10,4 +10,4 @@ metadata:
   ms.topic: unit
 durationInMinutes: 8
 content: |
-  [!include[](includes/2-what-is-github.md)]
+  [!include[](includes/2-what-is-github2.md)]