Fixed style guide link, added description

doc/developer/code-contribution.md

@@ -23,8 +23,10 @@ git checkout -b <branch name>
 
 ## Programming and Testing 
 
-1. Please review the [Mattermost Style Guide](developer/style-guide.md) prior to making changes.
+1. Please review the [Mattermost Style Guide](style-guide.md) prior to making changes.
 
+   To keep code clean and well structured, Mattermost users ESLint to check that pull requests adhere to style guidelines for React. Code will need to follow Mattermost's React style guidelines in order to pass the automated build tests when a pull request is submitted.
+   
 2. Please make sure to thoroughly test your change before submitting a pull request. 
 
 ## Submitting a Pull Request