* Update glossary with descriptions from Istio Vocabulary doc. (#3)
Also cleaned up a few other items such as the Pilot entry.
* Drop default service version
* Dropped too much, add back that each service version has a default
* Update service.md
* Add note about service versions to service
* Update workload-name.md
* Add a glossary entry for Workload ID
Maps to source.uid and destination.uid.
* Fix typo in Workload Principal (worklooad)