Update docs/registering-users.md: add configuration for enabling public user registration on Dendrite (#3748)

* Update docs/registering-users.md: add configuration for enabling public user registration on Dendrite

Per the suggestion on https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/2545

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

* Set matrix_dendrite_client_api_registration_disabled to false

Mind "matrix_synapse_enable_registration" for Synapse is set to false by default.

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

@@ -100,10 +100,18 @@ If you'd rather **keep your server private** (public registration closed, as is
 
 To **open up user registration publicly** (usually **not recommended**), add the following configuration to your `inventory/host_vars/matrix.example.com/vars.yml` file:
 
+For Synapse:
+
 ```yaml
 matrix_synapse_enable_registration: true
 ```
 
+For Dendrite:
+
+```yaml
+matrix_dendrite_client_api_registration_disabled: false
+```
+
 After configuring the playbook, run the [installation](installing.md) command: `just install-all` or `just setup-all`
 
 If you're opening up registrations publicly like this, you might also wish to [configure CAPTCHA protection](configuring-captcha.md).