Add Gerrit path to README.rst

Change-Id: I8006be6c484dc1d7a253e4250d9ab1e7d3acae41

README.rst

diff --git a/README.rst b/README.rst
index 752ec32..1b86b6e 100644
--- a/README.rst
+++ b/README.rst
@@ -4,10 +4,13 @@
 
 WARNING - Do not make GitHub pull requests!
 -------------------------------------------
-Ceres development happens on Gerrit, including both repository hosting and code
-reviews. The GitHub Repository is a continuously updated mirror which is
-primarily meant for issue tracking. Please see our `contributing guide
-<http://ceres-solver.org/contributing.html>`_ for more details.
+
+Ceres development happens on `Gerrit
+<https://ceres-solver.googlesource.com/>`_, including both repository
+hosting and code reviews. The GitHub Repository is a continuously
+updated mirror which is primarily meant for issue tracking. Please see
+our `contributing guide <http://ceres-solver.org/contributing.html>`_
+for more details.
 
 The upstream Gerrit repository is::