Update and rename CONTRIBUTING to CONTRIBUTING.md

CONTRIBUTING → CONTRIBUTING.md

@@ -10,6 +10,7 @@ The following is a set of guidelines for contributing to ISIS3.
   * [Working on an existing issue](#working-on-an-issue)
   * [Working on an existing enhancement](#working-on-an-enhancement)
   * [Working on a new issue or enhancement](#working-on-a-new-issue)
+[Guidelines for contributing to the code base](#guidelines-for-contributing-to-the-code-base)
 [What can I expect from the ISIS3 development team](#What-can-I-expect-from-the-ISIS3-development-team)
   * [Response time](#Response-time)
   * [Feedback](#feedback)
@@ -27,12 +28,12 @@ The following is a set of guidelines for contributing to ISIS3.
 There's lots of ways to contribute to ISIS3.
 
 ### Working on an existing issue
-1. Assign the redmine issue to yourself. If you don't have the permission to do this please make a note on the issue that you would like to work on it.
+1. Assign the redmine issue to yourself. If you don't have the permission to do this, please make a note on the issue that you would like to work on it. Please contact <REGENT EMAIL HERE> for permission to work on an issue.
 2. Propose a solution on the redmine issue. 
-3. Work with other developers and the issue reporter to improve your solution.
-4. Add an impact statement to the redmine issue. If you don't have the permission to do this please make a note on the issue with the impact statement
-5. Make the changes on your fork of the ISIS3 main GitHub repo.
+3. Work with an ISIS3 developer, the issue reporter, and any other interested parties to get feedback on your solution. This may be an iterative process.
+4. Add an [impact statement](https://isis.astrogeology.usgs.gov/fixit/projects/isis/wiki/Impact_Statement) to the redmine issue. If you don't have the permission to do this, please make a note on the issue with the impact statement.
+5. Make the changes on your fork of the ISIS3 main GitHub repo. Follow the [Guidelines for contributing to the code base](#guidelines-for-contributing-to-the-code-base).
 6. Follow the Developer's Checklist to ensure your changes are ready for review.
-7. Make a pull request. Include the redmine issue number in the title of the pull request. Use the Fixes #<Insert issue number> format.
+7. Make a pull request. Include the redmine issue number in the title of the pull request. Use the "Fixes #<Insert issue number>" format.
 8. Work with your code reviewer, tester, and reporter to improve your changes. Your pull request will not be merged in until all parties approve the changes.
 9. Check in your test data. If you are an outside contributer, work with your code reviewer to ensure your tests and test data get checked in.