This marks **/docs/** as exclusively docs, and code that is autodoc'd as
inclusively docs.
That means that a change that purely modifies documentation files will *only*
run `docs` tasks, while a change that modifies autodoc'd source code will
*additionaly* run `docs` tasks. The tasks do not run by default.
MozReview-Commit-ID: G9tOK0AwtrI
--HG--
extra : rebase_source : 8dd971e5c9b0eb5f47895664a4ea49442f303ecb
extra : source : 0881de9b2b5e36ec37cc866f1d4af109da57a919
522245f2f2