Create information architecture for shared Crew/Ops Knowledgebase

We need to create a foundational structure for the content, aka information architecture, to organize everything. It will evolve over time through use, but this will set it up for a good start and help users "do the right thing". Crew Ops will use it for help-desk-like support and troubleshooting articles. Crews themselves will be able to use the same content self-service, Also Crews can create their own content. Content will span multiple crews over all time. Each crew and user should be uniquely identified.

The information architecture consists of:

1) basic site structure, down to at least 3 levels
2) reference dictionary of key EVALink terms, technologies, subsystems, components, etc.
3) reference dictionary of similar key terms, etc. for MDRS and crews
4) What types of content are in and out of scope
5) starting set of tags to use

No file, test, or entry point is named in the issue. Start from the five requested information-architecture deliverables: define a three-level site structure, term dictionaries for EVALink, MDRS, and crews, content boundaries, and initial tags; done means these structures and rules are documented for shared Crew/Ops use.

Written by the indexing model from the issue text.