some mistakes in readme about then chapter

[QSKOBE24]

i think It was negligence to forget the * punctuation。
FBLPromise<NSString *> *chainedStringPromise1 = [numberPromise then:^id(NSNumber *number) { return [self stringFromNumber:number]; }];

[Anthony Shoumikhin]

Nice catch @QSKOBE24 !
Do you mind to send a pull request our way with the fix?
Thank you!

[Deleted user]

Thank you for raising the issue. Updated the docs.