Remove recommendation to use prune_bundler in deployment docs

It's no longer necessary to support phased restarts.

docs/deployment.md

@@ -103,11 +103,6 @@ is unavailable would be nice as well. Here's how to do it:
 1. Don't use `preload!`. This dirties the master process and means it will have
 to shutdown all the workers and re-exec itself to get your new code. It is not compatible with phased-restart and `prune_bundler` as well.
 
-1. Use `prune_bundler`. This makes it so that the cluster master will detach itself
-from a Bundler context on start. This allows the cluster workers to load your app
-and start a brand new Bundler context within the worker only. This means your
-master remains pristine and can live on between new releases of your code.
-
 1. Use phased-restart (`SIGUSR1` or `pumactl phased-restart`). This tells the master
 to kill off one worker at a time and restart them in your new code. This minimizes
 downtime and staggers the restart nicely. **WARNING** This means that both your