Update contributors docs

Author: Zachary Eisinger

docs/contributors.md

@@ -1,17 +1,24 @@
 # Contributors
 
+Thank you for contributing! This action is targetted around setting up the dotnet cli and related sdks for GitHub actions. As part of that we use proxy settings (for self-hosted runners) and set-up nuget authentication for private feeds.
 
-# Checkin
+If you would like to contribute there are a few things to consider:
 
-- Do checkin source (src)
-- Do checkin build output (lib)
-- Do checkin runtime node_modules
-- Do not checkin 
+## Commands to use
 
-# Adding a dev dependency
+- npm run build - Compiles the action into a single js file at dist/index.js (Please check in the changes made by this command)
+- npm run test - Runs all tests under __tests__
+- npm run format - Runs formatting required to pass the lint test (Please check in the changes made by this command)
+- npm run update-installers - Updates the install-dotnet scripts in externals (Please check in the changes made by this command)
 
-Remember to update .gitignore.  
+## To check in or not to check in
 
-# Updating toolkit dependency
+- Do check in source (src)
+- Do check in index file (dist)
+- Do check in updates to install-dotnet scripts (externals)
+- Do not check in build output (lib)
+- Do not check in runtime (node_modules)
 
-Until released publically, update tgz packages in toolkit
+## Writing tests
+
+With any contribution please take time to consider how this can be tested to maintain high quality. Current tests can be found in the folder __tests__ for examples.