Updated CONTRIB file.

Change-Id: Ib464e31cf1431a0b3aa22d3b40d0340d57644890

CONTRIBUTING.md

@@ -5,16 +5,26 @@
 We'd love to accept your patches! Before we can take them, we 
 have to jump a couple of legal hurdles.
 
-Please fill out either the individual or corporate Contributor License Agreement
-(CLA).
+### Before you contribute
+Before we can use your code, you must sign the
+[Google Individual Contributor License Agreement](https://cla.developers.google.com/about/google-individual)
+(CLA), which you can do online. The CLA is necessary mainly because you own the
+copyright to your changes, even after your contribution becomes part of our
+codebase, so we need your permission to use and distribute your code. We also
+need to be sure of various other things—for instance that you'll tell us if you
+know that your code infringes on other people's patents. You don't have to sign
+the CLA until after you've submitted your code for review and a member has
+approved it, but you must do it before we can put your code into our codebase.
+Before you start working on a larger contribution, you should get in touch with
+us first through the issue tracker with your idea so that we can help out and
+possibly guide you. Coordinating up front makes it much easier to avoid
+frustration later on.
 
-  * 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).
+### Code reviews
+All submissions, including submissions by project members, require review. We
+use Github pull requests for this purpose.
 
-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
-accept your pull requests.
+### The small print
+Contributions made by corporations are covered by a different agreement than
+the one above, the
+[Software Grant and Corporate Contributor License Agreement](https://cla.developers.google.com/about/google-corporate).