self-signed-chain.rst might need an update

[Monviech]

Important notices

Before you add a new report, we ask you kindly to acknowledge the following:

• I have read the contributing guide lines at https://github.com/opnsense/docs/blob/master/CONTRIBUTING.md
• I have searched the existing issues and I am convinced that mine is new.

Describe the issue

PR: https://forum.opnsense.org/index.php?topic=42783.0

Since "Trust" has been rewritten, this tutorial section is now outdated:
https://github.com/opnsense/docs/blob/master/source/manual/how-tos/self-signed-chain.rst

Suggestions

Rewriting that section to fit the new menu would be beneficial, alternatively marking this one "Legacy" and implementing a new section for "Trust (new)" kind of like the IPsec section.

Describe alternatives you considered

N/A

Additional context

N/A

[Monviech]

@fichtner Your thoughts on this?