add some doc

Author: Laurent Cobos

lib/rspec/rails/fixture_file_upload_support.rb

@@ -14,9 +14,10 @@ def fixture_path
           @fixture_path ||= calculate_path
         end
 
+        # overrided accessor to support Rails 3.0..3.1
+        # because of ActionController::TestCase class to resolve fixture_path
+        # see https://apidock.com/rails/v3.0.0/ActionDispatch/TestProcess/fixture_file_upload
         def fixture_path=(value)
-          # Rails 3.0..3.1 are using ActionController::TestCase class to resolve fixture_path
-          # see https://apidock.com/rails/v3.0.0/ActionDispatch/TestProcess/fixture_file_upload
           if ActionController::TestCase.respond_to?(:fixture_path)
             ActionController::TestCase.fixture_path = value
           end