docs: Refactor master accounts page

This rewrite should more clearly document the feature, along with a better example and additional links for reference.

docs/content/config/account-management/supplementary/master-accounts.md

@@ -4,19 +4,49 @@ title: 'Account Management | Master Accounts (Dovecot)'
 
 ## Introduction
 
-A master account is able to login as any configured user. This is useful for administrative tasks like hot backups.
+A master account:
+
+- Can login as any user (DMS account) and access their mailbox.
+- Is not associated to a separate DMS account, nor is it a DMS account itself.
+
+This feature is useful for administrative tasks like hot backups.
+
+!!! note
+
+    This feature is presently [not supported with LDAP][dms::feature::dovecot-master-accounts::caveat-ldap] account provisioning.
+
+
+??? abstract "Technical Details"
+
+    [The _Master Accounts_ feature][dms::feature::dovecot-master-accounts] in DMS configures the [Dovecot Master Users][dovecot-docs::auth::master-users] feature with the Dovecot setting [`auth_master_user_separator`][dovecot-docs::config::auth-master-user-separator] using the upstream default value (`*`).
 
 ## Configuration
 
-It is possible to create, update, delete and list master accounts using `setup`. See `setup help` for usage.
+The DMS `setup` CLI can create, update, delete, and list master accounts. Run `setup help` for usage.
 
-This feature is presently [not supported with LDAP](https://github.com/docker-mailserver/docker-mailserver/pull/2535).
+## Login via Master Account
 
-## Logging in
+To login as another DMS account (`user@example.com`) with POP3/IMAP, use the following credentials format:
 
-Once a master account is configured, it is possible to connect to any users mailbox using this account.
+- Username: `<LOGIN USERNAME>*<MASTER USER>` (`user@example.com*admin`)
+- Password: `<MASTER PASSWORD>`
 
-Log in over POP3/IMAP using the following credential scheme:
+!!! example "Verify login functionality"
 
-- Username: `<EMAIL ADDRESS>*<MASTER ACCOUNT NAME>`
+    In the DMS container, you can verify with the `testsaslauthd` command:
-- Password: `<MASTER ACCOUNT PASSWORD>`
+
+    ```bash
+    # A regular DMS account to test login through a master account:
+    setup email add user@example.com secret
+    # Add a new master account:
+    setup dovecot-master add admin top-secret
+
+    testsaslauthd -u 'user@example.com*admin' -p 'top-secret'
+    ```
+
+    Alternatively, any mail client should be able to login the equivalent credentials.
+
+[dms::feature::dovecot-master-accounts]: https://github.com/docker-mailserver/docker-mailserver/pull/2535
+[dms::feature::dovecot-master-accounts::caveat-ldap]: https://github.com/docker-mailserver/docker-mailserver/pull/2535#issuecomment-1118056745
+[dovecot-docs::auth::master-users]: https://doc.dovecot.org/configuration_manual/authentication/master_users/
+[dovecot-docs::config::auth-master-user-separator]: https://doc.dovecot.org/settings/core/#core_setting-auth_master_user_separator