[docs] sending bugs to docs ... was sum( ) in generator

[Laura Creighton]

re: https://docs.python.org/3.5/bugs.html 
("If you’re short on time, you can also email your bug report to 
docs at python.org. ‘docs@’ is a mailing list run by volunteers; your 
request will be noticed, though it may take a
while to be processed.").

Should we change this?  

Laura