documentation: Clean up references to 'Gerrit2'

Now that the 2.x code base is over a year old, and has been in
production for almost a full year, its time to stop calling this
'Gerrit2' and start referring to it by the complete project name,
Gerrit Code Review.

Change-Id: Ifb37dd63b94ed7e1b938511aa0fc2a6ad3c981d6
Signed-off-by: Shawn O. Pearce <sop@google.com>

Documentation/install.txt

diff --git a/Documentation/install.txt b/Documentation/install.txt
index 1ce02a92a..19472eb 100644
--- a/Documentation/install.txt
+++ b/Documentation/install.txt
@@ -1,5 +1,5 @@
-Gerrit2 - Installation Guide
-============================
+Gerrit Code Review - Installation Guide
+=======================================
 
 You need a SQL database to house the Gerrit2 metadata.  Currently
 H2, MySQL and PostgreSQL are the only supported databases.