Mention PyPI in the README
Mention PyPI in the README

similar to #11

google/yapf,hayd/yapf,jamesblunt/yapf,nikolamilosevic86/yapf,google/yapf,bygloam/yapf,sbc100/yapf,thurday/yapf,abduld/yapf,wklken/yapf,elviswf/yapf,dmoliveira/yapf,lucius-feng/yapf,sbc100/yapf,ambv/yapf