Add rubocop to bundler readme

plugins/bundler/README.md

@@ -15,7 +15,7 @@
   - calls `bundle exec <gem executable>` otherwise
 
 Common gems wrapped by default (by name of the executable):
-`annotate`, `cap`, `capify`, `cucumber`, `foodcritic`, `guard`, `hanami`, `irb`, `jekyll`, `kitchen`, `knife`, `middleman`, `nanoc`, `pry`, `puma`, `rackup`, `rainbows`, `rake`, `rspec`, `shotgun`, `sidekiq`, `spec`, `spork`, `spring`, `strainer`, `tailor`, `taps`, `thin`, `thor`, `unicorn` and `unicorn_rails`.
+`annotate`, `cap`, `capify`, `cucumber`, `foodcritic`, `guard`, `hanami`, `irb`, `jekyll`, `kitchen`, `knife`, `middleman`, `nanoc`, `pry`, `puma`, `rackup`, `rainbows`, `rake`, `rspec`, `rubocop`, `shotgun`, `sidekiq`, `spec`, `spork`, `spring`, `strainer`, `tailor`, `taps`, `thin`, `thor`, `unicorn` and `unicorn_rails`.
 
 ## Configuration