Add categories for entites (e.g. "administrative entity", "clinical entity")

[gaurav]

Is your feature request related to a problem? Please describe.
While CCDH entities are grouped into various categories (e.g. "administrative entity", "clinical entity"), this information is not present in the documentation in any way. Adding these categories might help organize or visualize the entities in ways that are easier to navigate. It might also be useful to have a high-level document that describes the various categories, with pointers to the "central" entity in that category.

Describe the solution you'd like

1. Update the CRDCH model documentation to include a high-level document that describes the various categories of entities.
2. (Possibly) Use the LinkML tag property to indicate which category each
3. Modify sheet2linkml so that it generates these tags automatically from the model definition in Google Sheet.
4. Modify markdowngen so that it uses this information to provide navigation features.

How important is this feature? Select from the options below:
• Medium - can do work without it; but it's important (e.g. to save time or for convenience)

When will use cases depending on this become relevant? Select from the options below:
• Mid-term - 2-4 months