Add anaconda badge for pluggy

Author: nicoddemus

README.rst

@@ -1,6 +1,6 @@
 pluggy - A minimalist production ready plugin system
 ====================================================
-|pypi| |versions| |travis| |appveyor|
+|pypi| |anaconda| |versions| |travis| |appveyor|
 
 
 This is the core framework used by the `pytest`_, `tox`_, and `devpi`_ projects.
@@ -66,6 +66,8 @@ A definitive example
     :target: https://travis-ci.org/pytest-dev/pluggy
 .. |appveyor| image:: https://img.shields.io/appveyor/ci/pytestbot/pluggy/master.svg
     :target: https://ci.appveyor.com/project/pytestbot/pluggy
+.. |anaconda| image:: https://anaconda.org/conda-forge/pluggy/badges/version.svg
+    :target: https://anaconda.org/conda-forge/pluggy
 
 .. links
 .. _pytest: