add instructions on how to use the gem on rails

README.rdoc

@@ -35,14 +35,20 @@ not regularly tested.
 
 == How To Install
 
+*NOTE*: if you are installing jruby-pg to use it with rails you'll
+ have to install it using bundler
+
 Install via RubyGems:
 
     gem install pg_jruby
 
 Install via Bundler, in your gemfile add the following:
 
     # Please note that the 1.0 is necessary to let bundler do its dependency management, as there is no .gemspec in the source.
-    gem 'pg_jruby', '0.17.1', :platform => :jruby, :git => 'git://github.com/headius/jruby-pg.git', :branch => :master
+    gem 'pg', '0.17.1', :platform => :jruby, :git => 'git://github.com/headius/jruby-pg.git', :branch => :master
+
+    # comment the activerecord-jdbcsqlite3-adapter line
+    # gem 'activerecord-jdbcsqlite3-adapter'
 
 == Copying