Merged r11657 from trunk.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/branches/2.3-stable@11658 e93f8b46-1217-0410-a6f0-8f06a7374b81

doc/UPGRADING

@@ -32,6 +32,16 @@ http://www.redmine.org/
    of the rmagick gem using:
      bundle install --without development test rmagick
 
+   Only the gems that are needed by the adapters you've specified in your database
+   configuration file are actually installed (eg. if your config/database.yml
+   uses the 'mysql2' adapter, then only the mysql2 gem will be installed). Don't
+   forget to re-run `bundle install` when you change config/database.yml for using
+   other database adapters.
+
+   If you need to load some gems that are not required by Redmine core (eg. fcgi),
+   you can create a file named Gemfile.local at the root of your redmine directory.
+   It will be loaded automatically when running `bundle install`.
+
 6. Generate a session store secret
    
    Redmine stores session data in cookies by default, which requires