Add back a CONTRIBUTING markdown file. (#1225)

Merged PR #1225.

.github/CONTRIBUTING.md

@@ -0,0 +1,14 @@
+# Contributor License Agreements
+
+We have a few legal steps to accept most community changes. If you're submitting
+a pull request to this repo, please fill out either the individual or corporate
+Contributor License Agreement (CLA).
+
+  * If you are an individual writing original source code and you're sure you
+    own the intellectual property, then you'll need to sign an [individual CLA](http://code.google.com/legal/individual-cla-v1.0.html).
+  * If you work for a company that wants to allow you to contribute your work,
+    then you'll need to sign a [corporate CLA](http://code.google.com/legal/corporate-cla-v1.0.html).
+
+Follow either of the two links above to access the appropriate CLA and
+instructions for how to sign and return it. Once we receive it, we'll be able to
+review/accept your PR.

README.md

@@ -231,17 +231,3 @@ that maintainer with no changes needing to be made.
 
 Once you've gotten approvals from the primary reviewer and the reviewers for
 any affected tools, the primary reviewer will merge your changes.
-
-#### Contributor License Agreements
-
-We have a few legal steps to accept most community changes. Please fill out
-either the individual or corporate Contributor License Agreement (CLA).
-
-  * If you are an individual writing original source code and you're sure you
-    own the intellectual property, then you'll need to sign an [individual CLA](http://code.google.com/legal/individual-cla-v1.0.html).
-  * If you work for a company that wants to allow you to contribute your work,
-    then you'll need to sign a [corporate CLA](http://code.google.com/legal/corporate-cla-v1.0.html).
-
-Follow either of the two links above to access the appropriate CLA and
-instructions for how to sign and return it. Once we receive it, we'll be able to
-review/accept your PR.