Adds smaller size banner

README.rst

@@ -1,4 +1,5 @@
 .. image:: http://docs.celeryproject.org/en/master/_images/celery-banner.png
+    :width: 120
 
 |build-status| |license| |wheel| |pyversion| |pyimp|
 

docs/history/changelog-1.0.rst

@@ -1881,3 +1881,4 @@ Sphinx started sucking by removing images from _static, so we need to add
 them here into actual content to ensure they are included :-(
 
 .. image:: ../images/celery-banner.png
+.. image:: ../images/celery-banner-small.png