Complement neurosift walkthrough with screenshots

[yarikoptic]

There is a
https://github.com/dandi/example-notebooks/blob/master/000458/FlatironInstitute/PSTH_neurosift_exploration.md by @magland and
@pauladkisson . We do have some video of going through neurosift UI posted as part of the https://docs.dandiarchive.org/user-guide-using/accessing-data/external-services/#neurosift , but I thought it would have been great to actually expand that PSTH_neurosift_exploration.md with actual screenshots of neurosift when performing any particular step -- it could guide users better and also might be more efficient presentation than video (requiring more time).

Could potentially use

<details>
<summary>step</summary> 

screenshot ref here 

</details>

constructs to make such steps foldable, e.g.

- To share your view, use the "Share this tab" on the left panel of Neurosift. Here's a link with the predefined state intact.

Or was there some specific idea behind here which would preclude or discourage construction of such a walkthrough @magland @pauladkisson ?