Updated INSTALL doc for Rails 2.2.2

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@2600 e93f8b46-1217-0410-a6f0-8f06a7374b81

doc/INSTALL

@@ -7,7 +7,7 @@ http://www.redmine.org/
 
 == Requirements
 
-* Ruby on Rails 2.1
+* Ruby on Rails 2.2.2
 * A database:
   * MySQL (tested with MySQL 5)
   * PostgreSQL (tested with PostgreSQL 8.1)