Update best practices for reporting data

[fjclark]

Proposed Change

Update the "best practices for reporting data" section, in particular expanding on the utility/ limitations of common metrics. Also see Michael Gilson's comment in alchemistry/alchemical-best-practices#121.

Proposed Authors and Reviewers

Please confirm (before the end of January) that you are happy to author/ review and state when you're available. Authors, please say roughly when you plan to contribute the changes (no later than the end of May).

@JenkeScheen may like to add changes or review.

Proposed authors: @hannahbrucemacdonald, volunteeres wanted
Proposed reviewer: Volunteer wanted