[pkg] Tidy substvars usage in control file
The documentation package was missing a Built-Using field to record
the provenance of the templates.
Empty packages or meta packages do not require Depends on a specific
Python version, so we can remove the relevant substvars.
HTTP cache management
=====================
.. automodule:: cubicweb.web.httpcache
Cache policies
--------------
.. autoclass:: cubicweb.web.httpcache.NoHTTPCacheManager
.. autoclass:: cubicweb.web.httpcache.MaxAgeHTTPCacheManager
.. autoclass:: cubicweb.web.httpcache.EtagHTTPCacheManager
.. autoclass:: cubicweb.web.httpcache.EntityHTTPCacheManager
Exception
---------
.. autoexception:: cubicweb.web.httpcache.NoEtag
Helper functions
----------------
.. autofunction:: cubicweb.web.httpcache.set_http_cache_headers
.. NOT YET AVAILABLE IN STABLE autofunction:: cubicweb.web.httpcache.lastmodified