Remove reference to testing with test_after_commit

Author: lardawge

README.md

@@ -189,11 +189,6 @@ class MyActiveJobWorker < ::CarrierWave::Workers::ActiveJob::StoreAsset
 end
 ```
 
-### Testing with Rspec
-We use the after_commit hook when using active_record. This creates a problem when testing with Rspec because after_commit never gets fired
-if you're using transactional fixtures. One solution to the problem is to use the [TestAfterCommit gem](https://github.com/grosser/test_after_commit).
-There are various other solutions in which case google is your friend.
-
 ## License
 
 Copyright (c) 2011 Larry Sprock