Use smaller banner image

README.rst

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

docs/templates/readme.txt

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