docs/index: GH shield title change: Star -> GitHub

Author: 1st1

docs/index.rst

@@ -4,7 +4,7 @@
 .. image:: https://img.shields.io/pypi/status/uvloop.svg?maxAge=2592000?style=plastic
     :target: https://pypi.python.org/pypi/uvloop
 
-.. image:: https://img.shields.io/github/stars/magicstack/uvloop.svg?style=social&label=Star
+.. image:: https://img.shields.io/github/stars/magicstack/uvloop.svg?style=social&label=GitHub
     :target: https://github.com/MagicStack/uvloop