Improve tutorial clarity

[garrettmflynn]

This PR provides a wide range of improvements to our tutorials based on the Dev Hackathon user tests.

Highlights include:

1. Explicitly named test data folders for each tutorial section (i.e. single_session_data/multi_session_dataset instead of data/dataset
2. Providing notice to create a DANDI account on the tutorial homepage
3. Linking the tutorial in the GUIDE internal documentation page
4. Align user tests and documentation with workflow changes

[CodyCBakerPhD]

docs encountering build problem

At a minimum from the log

/home/docs/checkouts/readthedocs.org/user_builds/nwb-guide/checkouts/772/docs/tutorials/multiple_sessions.rst:14: ERROR: Unexpected indentation.
/home/docs/checkouts/readthedocs.org/user_builds/nwb-guide/checkouts/772/docs/tutorials/multiple_sessions.rst:15: WARNING: Block quote ends without a blank line; unexpected unindent.

[CodyCBakerPhD]

Even slimmer! Fixed one typo, otherwise LGTM