updated for 2.4 tag

README.rdoc

@@ -12,6 +12,10 @@ Note: these instructions apply to releases 2.4.0 and above.
 
 Blacklight uses a new Rails feature called "templates". To install the Blacklight plugin into a new Rails application, run the following command (be sure to answer all of the installation questions):
 
+===Installing Blacklight 2.4 (recommended):
+  http://github.com/projectblacklight/blacklight/raw/2.4/template.rb
+
+=== Installing the "trunk", or master branch:
   rails ./blacklight-app -m http://github.com/projectblacklight/blacklight/raw/master/template.rb
 
 After the installation process, make note of the instructions for starting Solr and indexing data. Blacklight depends on Solr so be sure it is running.