explain how to add unique options to counter_cache and others...

README.md

@@ -143,8 +143,16 @@ like specific a different column name, you can:</b>
 
 If you'd like to include only unique impressions in your count:
 
+    # default will be filtered by ip_address
     is_impressionable :counter_cache => { :column_name => :my_column_name, :unique => true }
 
+If you'd like to specify what sort of unique impression you'd like to save? Fear not,
+Any option you pass to unique, impressionist_count will use it as its filter to update_counters based on that unique option.
+
+    # options are any column in the impressions' table.
+    is_impressionable :counter_cache => { :column_name => :my_column_name, :unique => :request_hash }
+    is_impressionable :counter_cache => { :column_name => :my_column_name, :unique => :all }
+
 
 Adding column to model
 ----------------------
@@ -204,10 +212,21 @@ Contributing to impressionist
 * All testing is done inside a small Rails app (test_app).  You will find specs
   within this app.
 
+
+Want to run the tests? Ok mummy
+-------------------------------
+* bundle install
+* rails g impressionist
+* rake db:migrate && rake db:test:prepare
+* Run rake or rspec spec inside test_app dir
+* nothing else.
+* :wq
+
 Contributors
 ------------
 * [johnmcaliley](https://github.com/johnmcaliley)
 * [coryschires](https://github.com/coryschires)
 * [georgmittendorfer](https://github.com/georgmittendorfer)
+* [Antonio C Nalesso](https://github.com/nbit001)
 
 Copyright (c) 2011 John McAliley. See LICENSE.txt for further details.