added logo

docs/conf.py

@@ -144,7 +144,7 @@ spelling_word_list_filename='spelling_wordlist.txt'
 
 # The name of an image file (relative to this directory) to place at the top
 # of the sidebar.
-#html_logo = None
+html_logo = 'logo.png'
 
 # The name of an image file (within the static path) to use as favicon of the
 # docs.  This file should be a Windows icon file (.ico) being 16x16 or 32x32