ISSUE-4981: [Doc] update config docs

Original Issue: apache/pulsar#824638500800 
[Docs](https://pulsar.apache.org/docs/en/reference-configuration/#broker) not up-to-date with [conf](https://github.com/apache/pulsar/blob/branch-2.4/conf/broker.conf)

for example `isSchemaValidationEnforced=false` is not there