Add a feedback and testing/user testing page or section

[samglover]

Incorporate the details from this section, plus additional information about user testing. Include sample instructions, sample feedback, etc. The goal is to make it easy for new volunteers to get started testing interviews.

[samglover]

#517 added a feedback section, but it lacks information about user testing.

[nonprofittechy]

This can link to and summarize some of the content from this page: https://projects.suffolklitlab.org/legal-tech-class/docs/testing/testing

[samglover]

Could be useful to distinguish user testing from legal testing (i.e., looking for updates to the forms and law, or identifying workflow issues related to the legal problem.