Add documentation for how to use the table filtering section of scicat

[nickcrawford1]

This MR adds a documentation to for the Scicat table and column filtering as well as saving data. It is intended as a user guide on how to navigate and operate the filtering options along with information about what will return.

[LAShemilt]

Thanks so much for putting in the time to do this. There has been an initial start to the documentation on the dashboard but I think this goes further. It would be good to amalgamate the two docs.

I would say that the structure of this should be:
/docs/datasets/DashboardTableEditing.md

The current docs can be found here:
/docs/login/Dashboard.md

I would suggest that we keep the section on the Landing Page in /docs/login/Dashboard.md, but move the content on table filtering to /docs/datasets/DashboardTableEditing.md along with the new content on saving data.