[#62626728] improve --help output for vcloud-query

* link to main tool readme, not just vcloud-tools repo

* include example usage

* clarify what "types" are
[#62626728] improve markdown doc for vcloud-query
link to main README.md
focus on examples, improve usage notes
Merge pull request #85 from alphagov/query_docs_62626728

[#62626728] Improve vcloud-query documentation