Add Dovecot master instructions

docs/u_e-dovecot-static_master.md

@@ -0,0 +1,21 @@
+Random master usernames and passwords are automatically created on every restart of dovecot-mailcow.
+
+**That's recommended and should not be changed.**
+
+If you need the user to be static anyway, please specify two variables in `mailcow.conf`.
+
+**Both** parameters must not be empty!
+
+```
+DOVECOT_MASTER_USER=mymasteruser
+DOVECOT_MASTER_PASS=mysecretpass
+```
+
+Run `docker-compose up -d` to apply your changes.
+
+The static master username will be expanded to `DOVECOT_MASTER_USER@mailcow.local`.
+
+To login as `test@example.org` this would equal to `test@example.org*mymasteruser@mailcow.local` with the specified password above.
+
+A login to SOGo is not possible with this username. A click-to-login function for SOGo is available for admins as described [https://mailcow.github.io/mailcow-dockerized-docs/debug-admin_login_sogo/](here).
+No master user is required.

mkdocs.yml

@@ -79,14 +79,15 @@ nav:
       - 'Using an external DNS service': 'u_e-unbound-fwd.md'
   - 'Dovecot':
       - 'Enable "any" ACL settings': 'u_e-dovecot-any_acl.md'
-      - 'Public folders': 'u_e-dovecot-public_folder.md'
       - 'Expunge a Users mails': 'u_e-dovecot-expunge.md'
       - 'Customize/Expand dovecot.conf': 'u_e-dovecot-extra_conf.md'
+      - 'FTS (Solr)': 'u_e-dovecot-fts.md'
+      - 'IMAP IDLE interval': 'u_e-dovecot-idle_interval.md'
       - 'Mail crypt': 'u_e-dovecot-mail-crypt.md'
       - 'More Examples with DOVEADM': 'u_e-dovecot-more.md'
       - 'Move vmail volume': 'u_e-dovecot-vmail-volume.md'
-      - 'IMAP IDLE interval': 'u_e-dovecot-idle_interval.md'
-      - 'FTS (Solr)': 'u_e-dovecot-fts.md'
+      - 'Public folders': 'u_e-dovecot-public_folder.md'
+      - 'Static master user': 'u_e-dovecot-static_master.md'
   - 'Nginx': 
      - 'Custom sites': 'u_e-nginx.md'
      - 'Create subdomain webmail.example.org': 'u_e-webmail-site.md'