Tutorial feedback: EFP first study page

[becky-gilbert]

This PR addresses part of #436 (but should not close that issue).

This PR updates the Lookit tutorial's "first study" section with up-to-date screenshots and text edits to reflect UI changes, e.g.

• separate 'edit study ad' and 'edit study design' pages
• different buttons on the study details page (e.g. no "take action" button)
• different page navigation sequence for editing/saving study ad/design
• up-to-date/corrected link to frame documentation that is embedded in the instructions for "Lookit tutorial part 1"
• updated instructions for finding developer tools
• new error example (EFP doesn't produce "missing parameter" error anymore..?)

It now mentions where researchers can go to find info on EFP frame parameters (part of the feedback from #436).

And it now points users to our 2FA docs, in case of problems logging in (part of the feedback from #436).