add support message (fsspec#691)

Author: martindurant

README.rst

@@ -16,3 +16,14 @@ For documentation, go to readthedocs_.
 .. |Doc Status| image:: https://readthedocs.org/projects/gcsfs/badge/?version=latest
     :target: https://gcsfs.readthedocs.io/en/latest/?badge=latest
     :alt: Documentation Status
+
+Support
+-------
+
+Work on this repository is supported in part by:
+
+"Anaconda, Inc. - Advancing AI through open source."
+
+.. raw:: html
+
+    <a href="https://anaconda.com/"><img src="https://camo.githubusercontent.com/b8555ef2222598ed37ce38ac86955febbd25de7619931bb7dd3c58432181d3b6/68747470733a2f2f626565776172652e6f72672f636f6d6d756e6974792f6d656d626572732f616e61636f6e64612f616e61636f6e64612d6c617267652e706e67" alt="anaconda logo" width="40%"/></a>