Removed references to TLS as primary auth method

[jaxoncreed]

TLS as a primary form of authentication should be deprecated in favor of a oidc. TLS may still be used as a form of credentials under oidc. All concerns about needing completely decentralized identity systems will be solved with an eventual implementation of DiD.

[RubenVerborgh]

Not opposed, just checking if this has been checked with @timbl?

[jaxoncreed]

@RubenVerborgh I'm going to submit this for discussion at the w3c working group meeting too, so we'll have plenty of time for input.

[elf-pavlik]

:+1: and if this PR will not land this month it should at least get marked with at risk

[michielbdejong]

Feedback we got from @timbl and @kidehen (in my own words): webid-tls should still be mentioned as a 'MAY' for client-storage, and as a 'SHOULD' for user-IDP login method ('openid + TLS bridge')