The behavior of *Key Usage* and *Extend Key Usage* is not totally clear
at the docs.
This change clarifies a little bit about when these extensions will be
ignored or mandatory.
This change only documents the behavior of certificate authentication
when *Login with email* is disabled. In this way people don't get
confused about it.
KEYCLOAK-4335: updated the punctuation
KEYCLOAK-4335: removed a redundant caption
KEYCLOAK-4335: fixed a typo; reworded the truststore element description