Requested new feature: include content files for each tab

[jcf2]

Basic Idea:
If we had an automatic inclusion of a file (e.g. .md) in each tab, we wouldn't have to fill it unless we needed it, but wouldn't need to go back and get changes every time we wanted to add one.

The display location (and possibly form?) could vary by tab. For example, on the Overview tab, fitting in a text section at the bottom makes sense, and seems like it would fit well. On a tab with potentially long output like Discrepancies, that layout might make it annoying to get to, so top (or side?) placement might be nicer there. One idea would be to have separate predefined "top" and "bottom" files for header/footer type sections.

These displayed sections might also be collapsible sections and if so we might vary the default [open vs closed] as well. There could also be a popout box that opens on a 'Learn more' type button, or after a quick sentence intro.

the alternative if we start proliferating too many individual files is a single .csv or json that would have say a column [or multiple] that defines the location the content is supposed to go, and then the next column contains the text. The text column can be provided in markdown in order to include desired formatting.

[mepearson]

Added