branchSharelinkDelegate doc update (#639)
branchSharelinkDelegate doc update (#639)

* Updated the docs to show BranchShareLink usage.


BranchMetrics/iOS-Deferred-Deep-Linking-SDK,BranchMetrics/ios-branch-deep-linking,BranchMetrics/ios-branch-deep-linking,BranchMetrics/iOS-Deferred-Deep-Linking-SDK,BranchMetrics/ios-branch-deep-linking,BranchMetrics/ios-branch-deep-linking