Update CONTRIBUTING.md

Specify to not use #region

Author: tilkinsc

CONTRIBUTING.md

@@ -42,4 +42,5 @@ public void Example(int argName)
 2. Push changes to a new local branch to the 'dev' branch. ('contributor-feature' -> 'dev')
 3. You are encouraged to start a PR early so we can spy on what you are working on!
 4. Versions should not be bumped at all
-5. gitignore is free game add anything that fits
+5. gitignore is free game add anything that fits
+6. Do not use #region