Document how to use user certificates in KEDA components

[JorTurFer]

Right now, we use self-signed certificates for some communications, and this usage will increase with incoming features.
This is not secure at all and KEDA brings the option to provide custom certificates for improving the security by managing the CA for high security production scenarios, but it's poorly documented. I'd like to have the process well documented (just the way to provide the certificates generated somehow) as part of the docs and maybe a blog post explaining how to automatize the process with a 3rd party software like cert-manager

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. Thank you for your contributions.

[JorTurFer]

I still have to write the blogpost

[JorTurFer]

I think that this is completed, the documentation was updated and the post was released 😄