Add textproc/py-markovify version 0.7.2

Markovify is a simple, extensible Markov chain generator. Right now,
its primary use is for building Markov models of large corpora of
text and generating random sentences from that.

Its features include:
* Simplicity. "Batteries included," but it is easy to override key methods.
* Models can be stored as JSON, allowing you to cache your results
  and save them for later.
* Text parsing and sentence generation methods are highly extensible,
  allowing you to set your own rules.

(ng0)