Add definition of TSC

Author: Relequestual

CHARTER.md

@@ -182,6 +182,8 @@ The JSON Schema project: The project which is housed by the OpenJS Foundation wh
 
 The JSON Schema Org: The people, policies, processes, activities, and artifacts, found within the GitHub json-schema-org.
 
+TSC: The Technical Steering Committee, delegated technical leadership for the JSON Schema project by the OpenJS Foundation.
+
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 This work is a derivative of the [WebdriverIO Project Governance Model](https://github.com/webdriverio/webdriverio/blob/main/GOVERNANCE.md).