Add WHO DHI license exception to README.md.

README.md

@@ -81,7 +81,10 @@ Used in the [docker compose setup](https://github.com/hitontology/docker).
 ## License
 
 HITO is dedicated to the public domain using Creative Commons Zero v1.0 Universal, see [LICENSE](LICENSE).
-However, a small amount SNOMED CT terms are used with special permission from SNOMED in <http://hitontology.eu/ontology/Snomed>.
+
+However, a small amount of SNOMED CT terms are used with special permission from SNOMED in <http://hitontology.eu/ontology/Snomed>.
+Another exception is <https://hitontology.eu/ontology/WhoDhi1-0>, which references the WHO Classification of Digital Health Interventions v1.0, which is licensed under the [Creative Commons Attribution-NonCommercial-ShareAlike 3.0 IGO Licence (CCBY-NC-SA 3.0 IGO)](https://creativecommons.org/licenses/by-nc-sa/3.0/igo/).
+
 Licensee agrees and acknowledges that HITO may not own all right, title, and interest, in and to the Materials and that the Materials may contain and/or reference intellectual property owned by third parties (“Third Party IP”).
 Acceptance of these License Terms does not grant Licensee any rights with respect to Third Party IP.
 Licensee alone is responsible for identifying and obtaining any necessary licenses or authorizations to utilize Third Party IP in connection with the Materials or otherwise.