Add gerrit instructions to the docs.

Change-Id: Ic98f20273f3ccbaeb8b4ca00c4ce0042a0d262f8
diff --git a/docs/source/building.rst b/docs/source/building.rst
index 36fecf9..fa81975 100644
--- a/docs/source/building.rst
+++ b/docs/source/building.rst
@@ -1,8 +1,8 @@
 .. _chapter-building:
 
-========
-Building
-========
+=====================
+Building Ceres Solver
+=====================
 
 Ceres source code and documentation are hosted at `code.google.com
 <http://code.google.com/p/ceres-solver/>`_.