* Update docs/configuring-playbook-turn.md: add a section for description about installing

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

* Update docs/configuring-playbook-turn.md and a related file

- Edit the introducion based on docs/configuring-playbook-client-element-web.md
- Adopt the commont format by creating the section "Adjusting the playbook configuration"
- Add the section "Extending the configuration"
- Move the section "Disabling Coturn" to the bottom

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

* Fix capitalization: Coturn → coturn

See: https://github.com/coturn/coturn. Note that "coturn" is not capitalized even on the start of a sentence, except some rare cases like on the releases page: https://github.com/coturn/coturn/releases

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

---------

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>
Co-authored-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

This reverts commit 9c01d875f3.

This is very confusing and messy.. but it's documented.
`ansible_become_*` variables actually take priority and override all `become_*`
variables set at the task level.

As such, using `ansible_become=true ansible_become_user=root` in
`inventory/hosts` causes issues because tasks that specify
`become: OTHER_USER` will be forced to run as `root` due to
`ansible_become_user`.

For some of these, the `ansible_` prefix does not seem to be needed,
but it's the canonical way to do things and it may become required in
newer Ansible versions.

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3237

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/570

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/641

Putting a lot of comments inbetween `[matrix-servers]` and the example
host line may make someone decide to clean up the comment
and accidentally skip-over the `[matrix-servers]` part.