miscellaneous README updates
miscellaneous README updates

- formatting
- Xcode version update

Johnykutty/SwiftLint,jeffreybergier/SwiftLint,victorpimentel/SwiftLint,realm/SwiftLint,firebase/SwiftLint,realm/SwiftLint,lyft/SwiftLint,realm/SwiftLint,lyft/SwiftLint,firebase/SwiftLint,Johnykutty/SwiftLint,Johnykutty/SwiftLint,firebase/SwiftLint,realm/SwiftLint,firebase/SwiftLint,lyft/SwiftLint,jeffreybergier/SwiftLint,Johnykutty/SwiftLint,victorpimentel/SwiftLint,lyft/SwiftLint,jeffreybergier/SwiftLint,victorpimentel/SwiftLint,victorpimentel/SwiftLint,jeffreybergier/SwiftLint