LDAP guide: explain LDAP operation flow, add glossary and troubleshooting sections
LDAP guide: explain LDAP operation flow, add glossary and troubleshooting sections

Co-authored with @lukebakken.

rabbitmq/rabbitmq-website,rabbitmq/rabbitmq-website,rabbitmq/rabbitmq-website,rabbitmq/rabbitmq-website,rabbitmq/rabbitmq-website