Avoid "should be" and "shall be" where possible

[Nat Sakimura]

It makes it unclear who is responsible for it.

There are two instances of “should be” and four relevant instances of “shall be”.

One on 5.7.3 reads a bit weird as well. It goes:

In addition, this profile

1. requires that jwks_uri endpoints shall be served over TLS;

‌

[Dave Tonge]

https://bitbucket.org/openid/fapi/pull-requests/477

[Dave Tonge]

PR merged