…ws_vpc_security_group_egress_rule`

* `ip_protocol` was marked as `Required` in the schema but `Optional` in the docs
* `security_group_id` is `Required` but was `Optional` in the schema
* Try to clarify the situations where `Optional` arguments are actually `Required`
* Make examples less confusing by using a single port; using different ports makes it look like some kind of port mapping

Co-authored-by: Justin Retzolk <[email protected]>