Found this on Cisco Community that pretty explain it all as for the Construct of an URI: ( Thanks to HAPRESTO )
https://community.cisco.com/t5/network-devices/how-to-list-all-yang-modules-used-by-the-restconf-server-on-ios/td-p/3570376
As RESTCONF was fully standardized in January 2017 so many implementations are still based on “Drafts” of RESTCONF.
The first version of IOS XE that supports standard RESTCONF is 16.6.1 for routing platforms (CSR, ISR, ASR, etc). This query works against a 16.6.1 CSR (or IOS XEv). (Updated with your devices credentials of course
curl -X GET \
https://<IP>/restconf/data/ietf-yang-library:modules-state/ \
-H ‘authorization: Basic dmFncmFudDp2YWdyYW50’
For the question on
“how can we derive the URIs from the YANG models a particular Cisco platform supports once we are able to list them?”
This is a URI construction key that I use to help show how a RESTCONF URL is created based on YANG models. 
