docs(sync): Add Github Wiki contributions

During the long-lived PR, multiple contributions to the existing Github Wiki were made, this commit applies those here and mentions the files and authors attributed to the changes:

JaapD: dkim.md + forward-only-mailserver-with-ldap-authentication.md

Added corrections to `setup.sh config dkim` command.
Added compatibility warning about 4096-bit key sizes or greater.
Added ldap tip. 

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fred727-temp: optional-config.md

Added a mention for `user-patches.sh`.

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Semir Patel: setup.sh.md + debugging.md

Minor corrections. Additionally corrected `tvial` references that had already been updated in this PR series.

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Stefan Neben: kubernetes.md

> Port 25 proxy protocol configuration in master.cf was missing
docs(sync): Add Github Wiki contributions
> IMAP with STARTTLS is also active, so we need that option here as well
docs(sync): Add Github Wiki contribution

docs/content/examples/uses-cases/forward-only-mailserver-with-ldap-authentication.md

@@ -105,5 +105,9 @@ You see that besides `query_filter`, I had to customize as well `result_attribut
 
     Another solution that serves as a forward-only mailserver is this: https://gitlab.com/docker-scripts/postfix
 
+!!! tip
+
+    One user reports only having success if `ENABLE_LDAP=0` was set.
+
 [github-file-readme-patches]: https://github.com/docker-mailserver/docker-mailserver/blob/master/README.md#custom-user-changes--patches
 [github-issue-1247]: https://github.com/docker-mailserver/docker-mailserver/issues/1247