feat: add example for content-type rule exclusion

[EsadCetiner]

Proposed changes

There isn't any examples in the documentation on how to safely allow additional Content Types without opening up a complete request body bypass. ModSecurity/Coraza relies on the Content Type header in order to parse a request body, and most users will either blindly disable the rule or add the forbidden content type to the list of allowed Content Types without fully understanding the impact.

Further comments

[EsadCetiner]

@theseion @fzipi The CI job isn't running for this PR. I think this is related to hardening the jobs?

error: unable to contact snap store

[fzipi]

I think you pushed your version of the theme/hugo-relearn that was older that the one upstream. Remember we are using submodules :)