Question on racial/ethnic groups may need further refinement

[hturner]

Updated to allow multiple selections part-way through 2020 survey, in response to user feedback and also this article: https://www.urban.org/urban-wire/separating-race-ethnicity-surveys-risks-inaccurate-picture-latinx-community, which references a detailed study: https://apps.npr.org/documents/document.html?id=4316468-2015nct-Race-Ethnicity-Analysis.

Wording/options could perhaps be refined for 2021 and we should look at the detailed study to help inform this.

[hturner]

Rather than "Other ethnic group" should use "Prefer to self identify" (also applies elsewhere I think)