README: Fix the restorationHandler closure signature  (#871)
README: Fix the restorationHandler closure signature  (#871)

* README: Fix restorationHandler method signature.
* README: Removed extra white spaces.

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