docs(contribute): add CLA note to code submission section

docs/content/misc/contribute.ngdoc

@@ -224,30 +224,39 @@ To run the E2E test suite:
 
 To create and submit a change:
 
-1. Create a new branch off the master for your changes:
+1. Please sign our Contributor License Agreement (CLA) before sending pull requests. For any code changes to be
+   accepted, the CLA must be signed. It's a quick process, we promise!
+
+   For individuals we have a [simple click-through form](http://code.google.com/legal/individual-cla-v1.0.html). For
+   corporations we'll need you to
+   [print, sign and one of scan+email, fax or mail the form](http://code.google.com/legal/corporate-cla-v1.0.html).
+
+
+2. Create a new branch off the master for your changes:
 
         git branch my-fix-branch
 
-2. Check out the branch:
+3. Check out the branch:
 
         git checkout my-fix-branch
 
-3. Create your patch, make sure to have plenty of tests (that pass).
+4. Create your patch, make sure to have plenty of tests (that pass).
 
-4. Commit your changes and create a descriptive commit message (the commit message is used to generate release notes,
+5. Commit your changes and create a descriptive commit message (the commit message is used to generate release notes,
    please check out our
    [commit message conventions](https://docs.google.com/document/d/1QrDFcIiPjSLDn3EL15IJygNPiHORgU1_OOAqWjiDU5Y/edit#)
    and our commit message presubmit hook `validate-commit-msg.js`):
 
         git commit -a
 
-5. Push your branch to Github:
+6. Push your branch to Github:
 
         git push origin my-fix-branch
 
-6. In Github, send a pull request to `angular:master`.
+7. In Github, send a pull request to `angular:master`.
 
-7. When the patch is reviewed and merged, delete your branch and pull yours — and other — changes
+
+8. When the patch is reviewed and merged, delete your branch and pull yours — and other — changes
 from the main (upstream) repository:
 
   1. To delete the branch in Github, run: