Update README.md and CONTRIBUTING.md with GitHub link.

PiperOrigin-RevId: 388691741
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 07824e0..d8c6e48 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -20,12 +20,13 @@
 The QUICHE repository is currently not set up to accept pull requests directly.
 If you would like to make a contribution, please follow these steps:
 
-1. Sign the Contributor License Agreement (see above).
-2. Create a Gerrit pull request at <https://quiche-review.googlesource.com>.
-3. Email a link to your pull request to <quiche-contribution@google.com>.
-4. An engineer will review your pull request and merge it internally.
+1.  Sign the Contributor License Agreement (see above).
+2.  Create a Gerrit pull request at <https://quiche-review.googlesource.com>, or
+    a GitHub pull request at <https://github.com/google/quiche/pulls>.
+3.  Email a link to your pull request to <quiche-contribution@google.com>.
+4.  An engineer will review your pull request and merge it internally.
 
 ## Community Guidelines
 
-This project follows [Google's Open Source Community
-Guidelines](https://opensource.google.com/conduct/).
+This project follows
+[Google's Open Source Community Guidelines](https://opensource.google.com/conduct/).
diff --git a/README.md b/README.md
index b30305f..60f24da 100644
--- a/README.md
+++ b/README.md
@@ -5,8 +5,11 @@
 powers Google's servers, Chromium, Envoy, and other projects. It is actively
 developed and maintained.
 
-The canonical open-source QUICHE repository is at
-https://quiche.googlesource.com/quiche.
+There are two public QUICHE repositories. Either one may be used by embedders,
+as they are automatically kept in sync:
+
+*   https://quiche.googlesource.com/quiche
+*   https://github.com/google/quiche
 
 To embed QUICHE in your project, platform APIs need to be implemented and build
 files need to be created. Note that it is on the QUICHE team's roadmap to