Add quick instructions for building the Zip. (#2819)
Add quick instructions for building the Zip. (#2819)

Added some instructions to build the zip. Will expand further with releasing information.
firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk