build(README): Use README.md instead of README.rst

Author: tony

MANIFEST.in

@@ -1,3 +1,3 @@
-include README.rst LICENSE CHANGES .tmuxp.yaml
+include README.md LICENSE CHANGES .tmuxp.yaml
 include requirements/*.txt
 recursive-include docs *.rst

setup.py

@@ -13,7 +13,7 @@
 with open('requirements/test.txt') as f:
     tests_reqs = [line for line in f.read().split('\n') if line]
 
-readme = open('README.rst').read()
+readme = open('README.md').read()
 history = open('CHANGES').read().replace('.. :changelog:', '')