Add additional details when marking content

Currently, when marking content, I select one of the categories (othering, stereotyping, etc). A new feature to integrate with this could be to have the expert advisory group add comments when they are marking something as racially biased, the users can also see the rationale for why they marked the phrase or expression as racially biased.

Start by tracing the Chrome extension's content-marking flow and how selected categories are stored and shown to users. Determine how advisory-group comments and the rationale for a racial-bias mark should be entered, persisted, and displayed. Done means marking supports an additional comment and users can view the associated rationale.

Written by the indexing model from the issue text.