Add contribution guide

What is the new feature

Add a contribution guide. Yen-Chen's email is also updated after moving from KIT to TUM.

CONTRIBUTING.md

@@ -63,7 +63,7 @@ We also additionally use [`cmake-format`](https://github.com/cheshirekow/cmake_f
     Co-authored-by: Another Name <another.address@example.com>
     ```
 
-6. Check whether yourself is listed in the `AUTHORS.txt` list. If not, add yourself in the alphabetic order. Your name will be included with when your merge request got merged.
+6. Check whether you are listed in the `AUTHORS.txt` list. If not, add yourself in the alphabetic order. Your name will be included when your merge request gets merged.
 
 ### Versions (Commits) Update in ICON