Add CRDCH Model Entities and Relationships diagram to CRDCH model documentation

[gaurav]

Describe the solution you'd like
Add the "CRDCH Model Entities and Relationships diagram" from the HioH slides for Oct 28, 2021 to the CRDCH Model.

How important is this feature? Select from the options below:
• Important - it's a blocker and can't do work without it

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

[gaurav]

@bfurner I'm assigning this to you to send me a high-resolution version of this diagram in (ideally) PDF or SVG or (non ideally) PNG format. Once you do that, I'll add it to https://cancerdhc.github.io/ccdhmodel/v1.1/home/. Alternatively, if you'd like to update https://github.com/cancerDHC/ccdhmodel/blob/main/model/docs/home.md yourself, go for it!

[bfurner]

@gaurav here is a link to the draw.io diagram.

draw.io can provide an embedded SVG or we can create a static image from an export. i assume the former is preferable, but i'm not sure what the markdown supports. let me know. thanks.

[gaurav]

@balhoff is working on an alternate approach using OWL and/or yUML.