docs(refactor): Large refactor + additions + fixes

Consistency pass, formatting cleanup and fixes, introduce admonitions, add front-matter.

---

docs: Add front-matter

---

docs: Fix and format links

- Some links were invalid (eg files moved or renamed)
- Some were valid but had invalid section headers (content removed or migrated)
- Some use `http://` instead of `https://` when the website supports a secure connection.
- Some already used the `[name][reference]` convention but often with a number that wasn't as useful for maintenance.
- All referenced docs needed URLs replaced. Opted for the `[name][reference]` approach to group them all clearly at the bottom of the doc, especially with the relative URLs and in some cases many duplicate entries.
- All `tomav` references from the original repo prior to switch to an organization have been corrected.
- Minor cosmetic changes to the `name` part of the URL, such as for referencing issues to be consistent.
- Some small changes to text body, usually due to duplicate URL reference that was unnecessary (open relay, youtous)
- Switched other links to use the `[name][reference]` format when there was a large group of URLs such as wikipedia or kubernetes. Github repos that reference projects related to `docker-mailserver` also got placed here so they're noticed better by maintainers. This also helped quite a bit with `mermaid` external links that are very long.
- There was a Github Wiki supported syntax in use `[[name | link]]` for `fetchmail` page that isn't compatible by default with MkDocs (needs a plugin), converted to `[name][reference]` instead since it's a relative link.

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docs: Update commit link for LDAP override script

Logic moved to another file, keeping the permalink commit reference so it's unaffected by any changes in the file referenced in future.

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docs: Heading corrections

Consistency pass. Helps with the Table of Contents (top-right UI) aka Document Outline.
docs: codefence cleanup

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docs: misc cleanup

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docs: Add Admonitions

Switches `<details>` usage for collapsible admonitions (`???`) while other text content is switched to the visually more distinct admoniton (`!!!` or `???+`) style.

This does affect editor syntax highlighting a bit and markdown linting as it's custom non-standard markdown syntax.

docs/content/config/security/fail2ban.md

@@ -1,17 +1,35 @@
-Fail2ban is installed automatically and bans IP addresses for 3 hours after 3 failed attempts in 10 minutes by default. If you want to change this, you can easily edit [config/fail2ban-jail.cf](https://github.com/tomav/docker-mailserver/blob/master/config/fail2ban-jail.cf).
-You can do the same with the values from fail2ban.conf, e.g dbpurgeage. In that case you need to edit [config/fail2ban-fail2ban.cf](https://github.com/tomav/docker-mailserver/blob/master/config/fail2ban-fail2ban.cf)
+---
+title: 'Security | Fail2Ban'
+hide:
+  - toc # Hide Table of Contents for this page
+---
 
-__Important__: The mail container must be launched with the NET_ADMIN capability in order to be able to install the iptable rules that actually ban IP addresses. Thus either include `--cap-add=NET_ADMIN` in the docker run commandline or the equivalent docker-compose.yml:
-```
-   cap_add:
-     - NET_ADMIN
-```
-If you don't you will see errors of the form
-```
+Fail2Ban is installed automatically and bans IP addresses for 3 hours after 3 failed attempts in 10 minutes by default. If you want to change this, you can easily edit [`config/fail2ban-jail.cf`][github-file-f2bjail].
+
+You can do the same with the values from `fail2ban.conf`, e.g `dbpurgeage`. In that case you need to edit [`config/fail2ban-fail2ban.cf`][github-file-f2bconfig].
+
+!!! attention
+    The mail container must be launched with the `NET_ADMIN` capability in order to be able to install the iptable rules that actually ban IP addresses.
+
+    Thus either include `--cap-add=NET_ADMIN` in the docker run commandline or the equivalent `docker-compose.yml`:
+
+    ```yaml
+    cap_add:
+      - NET_ADMIN
+    ```
+
+If you don't you will see errors the form of:
+
+```log
 iptables -w -X f2b-postfix -- stderr: "getsockopt failed strangely: Operation not permitted\niptables v1.4.21: can't initialize iptabl
 es table `filter': Permission denied (you must be root)\nPerhaps iptables or your kernel needs to be upgraded.\niptables v1.4.21: can'
 t initialize iptables table `filter': Permission denied (you must be root)\nPerhaps iptables or your kernel needs to be upgraded.\n"
 2016-06-01 00:53:51,284 fail2ban.action         [678]: ERROR   iptables -w -D INPUT -p tcp -m multiport --dports smtp,465,submission -
 j f2b-postfix
 ```
-You can also manage and list the banned IPs with the [setup.sh](https://github.com/tomav/docker-mailserver/wiki/Setup-docker-mailserver-using-the-script-setup.sh) script.
+
+You can also manage and list the banned IPs with the [`setup.sh`][docs-setupsh] script.
+
+[docs-setupsh]: ../setup.sh.md
+[github-file-f2bjail]: https://github.com/docker-mailserver/docker-mailserver/blob/master/config/fail2ban-jail.cf
+[github-file-f2bconfig]: https://github.com/docker-mailserver/docker-mailserver/blob/master/config/fail2ban-fail2ban.cf