Document how to import headers

[c100k]

Hello,

First, thanks for the hard work done on this lib ! Here is the thing :

I'm importing this lib in the Podfile with s.dependency 'SwiftyRSA/ObjC', '1.7.0'.

When adding the header #import <SwiftyRSA/SwiftyRSA.h> in my .m file, Xcode complains that SwiftyRSA does not exist when using it.

How to import the correct header ? Which one is it ? None of the headers present in the Pods folder work.

It would be cool to add a small line in the README.md on how to import for each language (Swift and ObjectiveC) ;)