Update CONTRIBUTING.md

Author: shalvah

CONTRIBUTING.md

@@ -1,8 +1,8 @@
 # Contributing
 
-Contributions are **welcome** and will be fully **credited**.
+Contributions are welcome.
 
-Please read and understand the contribution guide before creating an issue or pull request.
+NOTE: if your contribution changes the look of the generated documentation in some way, please include "before" and "after" screenshots in your pull request. 
 
 ## Etiquette
 
@@ -50,6 +50,4 @@ If the project maintainer has any additional requirements, you will find them li
 
 - **One pull request per feature** - If you want to do more than one thing, send multiple pull requests.
 
-- **Send coherent history** - Make sure each individual commit in your pull request is meaningful. If you had to make multiple intermediate commits while developing, please [squash them](http://www.git-scm.com/book/en/v2/Git-Tools-Rewriting-History#Changing-Multiple-Commit-Messages) before submitting.
-
 **Happy coding**!