pydoctor templates should set a canonical URL

[twisted-trac]

	@markrwilliams reported
Trac ID	trac#8996
Type	enhancement
Created	2017-01-15 21:18:17Z

Our pydoctor templates should set a canonical URL via a link tag, so that A Certain Search Engine will send people to the latest version of our documentation.

See https://docs.readthedocs.io/en/latest/canonical.html for more information.

Searchable metadata

trac-id__8996 8996
type__enhancement enhancement
reporter__markrwilliams markrwilliams
priority__normal normal
milestone__None None
branch__ 
branch_author__ 
status__new new
resolution__None None
component__core core
keywords__None None
time__1484515097061297 1484515097061297
changetime__1484515097061297 1484515097061297
version__None None
owner__None None

[adiroiban]

I have moved this here as it should be fixed in pydoctor
twisted/pydoctor#608