Add GitHub badge, fix typo in CHANGELOG.

Author: anntzer

Diff for: CHANGELOG.rst

@@ -7,7 +7,7 @@ v0.3
   ``MPLCAIRO_BUILD_TYPE``.
 - Added support for OpenType font features.
 - Added support for ``pdftex.map`` font effects (as in Matplotlib's
-  ``usetex_fonteffects.py`` example.
+  ``usetex_fonteffects.py`` example).
 - Fix zooming on macosx.
 
 v0.2

Diff for: README.rst

@@ -2,10 +2,13 @@
 A (new) cairo backend for Matplotlib
 ====================================
 
-|PyPI| |Fedora Rawhide|
+|GitHub| |PyPI| |Fedora Rawhide|
 
 |Azure Pipelines|
 
+.. |GitHub|
+   image:: https://img.shields.io/badge/github-anntzer%2Fmplcairo-brightgreen
+   :target: https://github.com/anntzer/mplcairo
 .. |PyPI|
    image:: https://img.shields.io/pypi/v/mplcairo.svg
    :target: https://pypi.python.org/pypi/mplcairo