Added three books to the to the 'Professional Development' list.

- How to Do What You Love & Earn What You’re Worth as a Programmer (Leanpub, By Reginald Braithwaite);
- What I've Learned From Failure (Leanpub, By Reginald Braithwaite);
- Why programmers work at night (Leanpub, By Swizec Teller).