Edit installing instructions (#3844)

* Replace "just run-tags install-all/setup-all,start" with "just install-all/setup-all"

Thanks to the tip by Slavi that the overhead of ensure-matrix-users-created is negligible.

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

* Edit installing instructions

- Move the anchor links to docs/just.md
- Add note about running "ensure-matrix-users-created" tags, if ansible-playbook's tags not "setup-all,ensure-matrix-users-created,start", ie. either "setup-all,start", "setup-email2matrix,start", "setup-aux-files,setup-corporal,start", or "setup-matrix-user-verification-service,start"

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

* Update descriptions about installation

- Introduce the most conservative and stable raw ansible-playbook command.
- Introduce the just commands on installing.md and maintenance-upgrading-services.md, not on quick-start.md, since it is too early for quick start guide readers who are just starting to climb learning curve to use the shortcuts.

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

* Update docs/configuring-playbook-etherpad.md: remove the note about ensure-matrix-users-created

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>

docs/registering-users.md

@@ -121,9 +121,9 @@ ansible-playbook -i inventory/hosts setup.yml --tags=setup-all,start
 
 **Notes**:
 
-- The shortcut commands with `just` program are also available: `just run-tags install-all,start` or `just run-tags setup-all,start`
+- The shortcut commands with the [`just` program](just.md) are also available: `just install-all` or `just setup-all`
 
-  `just run-tags install-all,start` is useful for maintaining your setup quickly when its components remain unchanged. If you adjust your `vars.yml` to remove other components, you'd need to run `just run-tags setup-all,start`, or these components will still remain installed. For more information about `just` shortcuts, take a look at this page: [Running `just` commands](just.md)
+  `just install-all` is useful for maintaining your setup quickly when its components remain unchanged. If you adjust your `vars.yml` to remove other components, you'd need to run `just setup-all`, or these components will still remain installed. Note these shortcuts run the `ensure-matrix-users-created` tag too.
 
 - If you're opening up registrations publicly like this, you might also wish to [configure CAPTCHA protection](configuring-captcha.md).