Clarify the role of CocoaPods plugin in the documentation #216

Expected/desired behavior

I would like to understand, why CocoaPods plugin exists/if it is necessary at all, or it's just a convenience/alternative to e.g. automatic integration.

Relevant integration setup

[x] CocoaPods cocoapods-xcremotecache plugin
[ ] Automatic integration using xcprepare integrate ...
[ ] Manual integration
[ ] Carthage