Under the $CONFD_DIR/src/confd/dyncfg directory of the ConfD distribution, the confd_dyncfg.yang module is included. This module defines the namespace of http://tail-f.com/ns/confd_dyncfg/1.0 which contains all the ConfD configuration parameters that can be modified dynamically at runtime, i.e. it is a subset of the namespace that defines the ConfD configuration file (confd.conf).
The best way to understand how to use this feature is through the example of confdconf/dyncfg in the bundled example collection.
You can also refer to Chapter 27.4.2 in the Advanced Topics of the ConfD 6.0 User Guide for more information.