Accept `cache: true` in partial renderer collection_caching.rb

Contributing guidelines suggested I float my idea here first before making a pull request in GitHub. Essentially, I used cache: true for a collection render and it was silently not correct. I originally went to Rubocop suggesting a cop to catch the incorrect option key, and someone suggested it just be aliased within rails itself. Would it would be worthwhile to accept both? I think it’s an understandable mistake considering dev environment by default has caching turned off, and the fact that it’s a keyword so it will “silently fail” instead of throwing an exception, and the fact that the correct keyword…seems less correct (maybe that’s just me)