docs(refactor): Restructure document hierarchy

Additionally rename `installation-examples.md` and split

docs/content/advanced/override-defaults/dovecot.md

@@ -1,59 +0,0 @@
----
-title: 'Override the Default Configs | Dovecot'
----
-
-## Add Configuration
-
-The Dovecot default configuration can easily be extended providing a `config/dovecot.cf` file.
-[Dovecot documentation](https://wiki.dovecot.org) remains the best place to find configuration options.
-
-Your `docker-mailserver` folder should look like this example:
-
-```txt
-├── config
-│   ├── dovecot.cf
-│   ├── postfix-accounts.cf
-│   └── postfix-virtual.cf
-├── docker-compose.yml
-└── README.md
-```
-
-One common option to change is the maximum number of connections per user:
-
-```cf
-mail_max_userip_connections = 100
-```
-
-Another important option is the `default_process_limit` (defaults to `100`). If high-security mode is enabled you'll need to make sure this count is higher than the maximum number of users that can be logged in simultaneously.
-
-This limit is quickly reached if users connect to the mail server with multiple end devices.
-
-## Override Configuration
-
-For major configuration changes it’s best to override the dovecot configuration files. For each configuration file you want to override, add a list entry under the `volumes` key.
-
-```yaml
-services:
-  mail:
-    volumes:
-      - maildata:/var/mail
-      - ./config/dovecot/10-master.conf:/etc/dovecot/conf.d/10-master.conf
-```
-
-## Debugging
-
-To debug your dovecot configuration you can use:
-
-- This command: `./setup.sh debug login doveconf | grep <some-keyword>`
-- Or: `docker exec -it <your-container-name> doveconf | grep <some-keyword>`
-
-!!! note
-    [`setup.sh`][github-file-setupsh] is included in the `docker-mailserver` repository.
-
-The `config/dovecot.cf` is copied internally to `/etc/dovecot/local.conf`. To check this file run:
-
-```sh
-docker exec -it <your-container-name> cat /etc/dovecot/local.conf
-```
-
-[github-file-setupsh]: https://github.com/docker-mailserver/docker-mailserver/blob/master/setup.sh