Clarify test running instructions

Author: henrik

README.md

@@ -700,11 +700,19 @@ Over 70 different people have contributed to the project, you can see them all h
 
 ## Development
 
+Run the tests like this:
+
+    # Start a Redis server in another tab.
+    redis-server
+
+    bundle
+    rake spec
+
 Source hosted at [GitHub](http://github.com/splitrb/split).
+
 Report Issues/Feature requests on [GitHub Issues](http://github.com/splitrb/split/issues).
-Discussion at [Google Groups](https://groups.google.com/d/forum/split-ruby)
 
-Tests can be ran with `rake spec`
+Discussion at [Google Groups](https://groups.google.com/d/forum/split-ruby).
 
 ### Note on Patches/Pull Requests