* Update docs for older appservice bridges to enable legacy authorization

* Update docs/configuring-playbook-bridge-appservice-discord.md

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

* Update docs/configuring-playbook-bridge-appservice-webhooks.md

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

* further fix formatting

---------

Co-authored-by: blotree <teruyo@touhou-project.com>
Co-authored-by: Slavi Pantaleev <slavi@devture.com>

Related to:

- https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1974
- https://github.com/mautrix/discord/issues/17
- https://github.com/mautrix/discord/issues/18
- https://github.com/mautrix/discord/issues/19

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/795
and https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/822

A better fix will come later: https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/825

We're getting reports of it being broken and I can confirm that the
bridge works well without it, so I don't see why we'd be asking
people to enable it.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/751

Related to #540 (Github Pull Request).

Well, `config.yaml` has been playbook-managed for a long time.
It's now extended to match the default sample config of the Discord
bridge.

With this patch, we also make `registration.yaml` playbook-managed,
which leads us to consistency with all other bridges.

Along with that, we introduce `./config` and `./data` separation,
like we do for the other bridges.

It didn't mention `matrix_appservice_discord_client_id` and
`matrix_appservice_discord_bot_token`, which makes it hard for
beginners.

Related to #105 (Github Pull Request).

Bridge is setup to work on the matrix side with this, but the discord invite link is not automatically generated.