added blurb about checking issues list before code submission

Contributing.md

@@ -2,7 +2,10 @@
 
 If you'd like to contribute to the Fluid Framework open source codebase, first of all, thank you! We'd love to see your ideas and appreciate your contributions, whether they be in the form of [bug reports, idea suggestions](https://github.com/microsoft/FluidFramework/wiki/Submitting-Bugs-and-Feature-Requests), [code submissions](https://github.com/microsoft/FluidFramework/wiki/PR-Guidelines), or just [trying out our platform](https://github.com/microsoft/FluidFramework/wiki/Repo-Basics).
 
-We have tried to make it as easy as possible to set up your local clone of the Fluid Framework so that you can hit the ground running. Let's get started!
+Before working on a **code submission**, check out the [issues list](https://github.com/microsoft/FluidFramework/issues). Issues labeled `help wanted` are good issues to submit a PR for. If you are contributing significant changes, please discuss with the assignee of the issue first before starting to work on the issue. 
+
+We have tried to make it as easy as possible to set up your local clone of the Fluid Framework so that you can hit the ground running. 
+Let's get started!
 
   * [Repo Basics](https://github.com/microsoft/FluidFramework/wiki/Repo-Basics)
   * [Client Code](https://github.com/microsoft/FluidFramework/wiki/Client)