Role: Undergraduate Learning Assistant vs. ULA

[ykharitonova]

Update the adding_bio assignment and Add a Troubleshooting section.

• If a tutor submitted a profile .md file but it doesn't show up on the staff page, check that instead of ULA the role is listed as Undergraduate Learning Assistant.

Alternatively, change the layout file,_layouts/staffer.html file to accept both Undergraduate Learning Assistant and ULA.