Refactor to remove sections and order entries.
fixed awkward wording
* removed terms that are widespread -- such as "column" and "interval" -- since there are too many ways to define them, in favor of allowing them to be defined in context on pages where they occur. For example, "interval" shows up in the JSON blob containing segment metadata, as well as in queries.
* removed sections -- it's hard for a new user to understand exactly why these terms are in those sections, or what that means, so better to allow specific definitions or the context in pages to impart those relationships.
* Added links between entries