Document export tables for rla_export

[sfsinger19103]

Give specs for the columns in the rla export csv files. What is meaning of each column? What range of values are expected? E.g., “T” and “F” in acvr.csv.

Shall we do this in the README, @nealmcb?

This is related to #768

[nealmcb]

I see value and synergy in documenting the colums via JSON Schema, as @kiniry has started in #261. Then they can hopefully also more easily be tied back into the formal spec, and the Java code. I'm assuming that there are then tools to make pretty documentation to refer to from the README.

[sfsinger19103]

Separate document created: docs/export_manual.md and docs/export_manual_docx` for user-side documentation of export files.

[nealmcb]

Closed in branch associated with #810