Added instructions to the README for contributing code.
Added instructions to the README for contributing code.

manuyavuz/ios-library,grosch/ios-library,ipmobiletech/ios-library,mikerowan/ios-library,grosch/ios-library,manuyavuz/ios-library,ipmobiletech/ios-library,zhangqinghe/ios-library,grosch/ios-library,mikerowan/ios-library,zhangqinghe/ios-library,manuyavuz/ios-library,zhangqinghe/ios-library,ipmobiletech/ios-library,mikerowan/ios-library