Incorporated wording changes into the CONTRIBUTING file that make some sentences easier to read.

CONTRIBUTING.md

@@ -5,15 +5,14 @@ Before we can use your code, you must sign the
 [Google Individual Contributor License Agreement](https://developers.google.com/open-source/cla/individual?csw=1)
 (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.
+codebase.  Therefore, 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 avoids frustrations later.
 
 ### Code reviews
 All submissions, including submissions by project members, require review. You