Separate out cards/ARD example into its own category

[rossfarrugia]

Feedback is that the ARD example is a bit lost on https://pharmaverse.github.io/examples/tlg/demographic.html and easily missed.

We could separate ARD into its own category between ADaM and TLG and add this example with more explanation of why ARD themselves could be useful such as enabling electronic QC comparison, across-TLG consistency checks, or ease of automated downstream medical writing document authoring.