Hookshot's end-to-bridge encryption needs MSC2409 and MSC3202 enabled
on the homeserver, but the playbook only turned them on for Meowlnir.
Hookshot's encryption defaults to the playbook-wide
`matrix_bridges_encryption_enabled` toggle, so turning that on gave
Hookshot encryption against a Synapse which was not set up for it, and
Hookshot then struggled in encrypted rooms.

The playbook already wires up Hookshot's other encryption prerequisite
(Valkey) and fails the run when the Redis settings are missing, so
being only half-automatic here was the odd one out.

Synapse sends the extra data only to appservices which ask for it in
their registration file, so turning these on affects no other
component.

The documentation told Hookshot users to set the two Synapse variables
by hand, and argued they should be enabled deliberately. That
contradicted what we already do for Meowlnir, so it is gone; the note
now matches the Meowlnir one and points out that other homeserver
implementations still need arranging by hand.

Closes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/5506

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>