docs: Adapt build to deploy the "sysadm" sphinx instance
Related to swh/infra/sysadm-environment#3154 (closed) Depends on swh/devel/swh-docs!162 (closed)
Test Plan
tox (happy)
Migrated from D6454 (view on Phabricator)
Related to swh/infra/sysadm-environment#3154 (closed) Depends on swh/devel/swh-docs!162 (closed)
tox (happy)
Migrated from D6454 (view on Phabricator)