to prevent docker from using dir instead of file

added docs, added seperate service for database, pr comments

better path handling, fixed some mistakes

enable by default v2 api prefix for ma1sd

We can undo this once https://github.com/ma1uta/ma1sd/issues/44 gets
resolved.

Related to #508 (Github Pull Request).

Jitsi 4548-1 update

Typo STMP -> SMTP

Prevent 404s when Riot tries to retrieve domain-specific config.json

Riot unconditionally asks for a config.${document.domain}.json, c.f.
https://github.com/vector-im/riot-web/blame/develop/src/vector/getconfig.ts#L24

Document how to administer synapse database via tunneled web-frontend

Fixes #494 (Github Issue).

Add note about ask-become-pass

This flag is necessary for Ansible to ask for the sudo password when using the non-root option as documented in the `hosts` file. Otherwise, Ansible errors out with `missing sudo password`.

Fix typo in validation

This is mostly here to guard against problems happening
due to server migration and doing `chown -R matrix:matrix /matrix`.

Normally, the file is owned by `1000:1000`, as expected.

If ownership changes, Dimension could still start, but it will fail the
first time it tries to write to the database. Explicitly chowning
before startup guards against this.

Related to #485 and #486 (Github Pull Requests).
Also related to ccc7aaf0ce.

Dimension runs as the `node` user in the container (`1000:1000`).
It doesn't seem like we have a way around it. Thus, its configuration
must also be readable by that user (or group, in this case).

We don't really need to fail in such a spectactular way,
but it's probably good to do. It will only happen for people
who are defining their own user/group id, which is rare.

It seems like a good idea to tell them that this doesn't work
as they expect anymore and to ask them to remove these variables,
which otherwise give them a fake sense of hope.

Related to #486 (Github Pull Request).

Related to #485 (Github Pull Request).

Remove default UID/GID

If one runs the playbook with `--tags=setup-all`, it would have been
fine.

But running with a specific tag (e.g. `--tags=setup-riot-web`) would
have made that initialization be skipped, and the `matrix-riot-web` role
would fail, due to missing variables.