mention `gem :facets, require: (value)` with an array in the README

[benatkin]

In the README it has a good section on including individual components. Still I wasn't sure about adding requires to my rails config directory, so I checked to see if I could add them in my Gemfile – and, I can! From the bundler docs:

gem "redis", :require => ["redis/connection/hiredis", "redis"]

[brandonzylstra]

https://bundler.io/v2.4/man/gemfile.5.html