Documentation enhancements to mutual TLS configuration

1. Add a section "Verify using a browser" to our mutual TLS documentation.
2. There is a task "Import the server certificate into the client truststore" if the task is done with "security command" I don't know where the server certificate is located and how to find the location

The first point is already addressed in downstream documentation[1]. This issue is to add these to our upstream docs.

[1] https://access.redhat.com/documentation/es-es/red_hat_jboss_enterprise_application_platform/8-beta/html-single/configuring_ssltls_in_jboss_eap/index#enabling-two-way-ssl-tls-for-management-interfaces-and-applications_default , see for example the "Verify using a browser" section