Freeform language style guide

[stuartpb]

Proposed in opws/opws-dataset#194 - while that issue made the good point that language too codified is an anti-pattern for language that should be represented in actual code (ie. structured fields), there should probably be some best practices around writing en_US memos, like not using first/second/third person pronouns (describe it as "the site", etc).

These kinds of rules probably also extend out to other languages.

[stuartpb]

opws/opws-dataset#252 (comment) also had some good points about consistency in naming entries in the legal list.