Tweak RSpec instructions (#540)

Author: eliotsykes

README.md

@@ -161,43 +161,39 @@ It is not required to send `SPLIT_DISABLE=false` to activate Split.
 
 
 ### Rspec Helper
-To aid testing with RSpec, write `split_helper.rb` and call `use_ab_test(alternatives_by_experiment)` in your specs as instructed below:
+To aid testing with RSpec, write `spec/support/split_helper.rb` and call `use_ab_test(alternatives_by_experiment)` in your specs as instructed below:
 
 ```ruby
-# Recommended path for this file is 'spec/support/split_helper.rb'
+# Create a file with these contents at 'spec/support/split_helper.rb'
+# and ensure it is `require`d in your rails_helper.rb or spec_helper.rb
 module SplitHelper
+
+  # Force a specific experiment alternative to always be returned:
+  #   use_ab_test(signup_form: "single_page")
+  #
+  # Force alternatives for multiple experiments:
+  #   use_ab_test(signup_form: "single_page", pricing: "show_enterprise_prices")
+  #
   def use_ab_test(alternatives_by_experiment)
     allow_any_instance_of(Split::Helper).to receive(:ab_test) do |_receiver, experiment|
-        alternatives_by_experiment.fetch(experiment) { |key| raise "Unknown experiment '#{key}'" }
+      alternatives_by_experiment.fetch(experiment) { |key| raise "Unknown experiment '#{key}'" }
     end
   end
 end
-```
 
-Needs to ensure it `required` by rails_helper.rb or spec_helper.rb
-```ruby
 # Make the `use_ab_test` method available to all specs:
 RSpec.configure do |config|
   config.include SplitHelper
 end
 ```
 
-Example:
+Now you can call `use_ab_test(alternatives_by_experiment)`  in your specs, for example:
 ```ruby
 it "registers using experimental signup" do
-
   use_ab_test experiment_name: "alternative_name"
-
   post "/signups"
-
   ...
 end
-
-# Force a specific experiment alternative to always be returned:
-#   use_ab_test(signup_form: "single_page")
-#
-# Force alternatives for multiple experiments:
-#   use_ab_test(signup_form: "single_page", pricing: "show_enterprise_prices")
 ```