Update transfer commitment documentation

Respects the movement of the transfer token as queryString into the header

docs/users/api-spec-resources.md

@@ -773,9 +773,11 @@ The response is a JSON of the commitment including the following fields that ide
   }
 }
 ```
-### POST /v1/domains/:id/projects/:id/transfer-commitment/:id?token=:token
+### POST /v1/domains/:id/projects/:id/transfer-commitment/:id
 Transfers the commitment from a source project to a target project.
 Requires a project-admin token.
+Requires a transfer token in the request header:
+`Transfer-Token: [value]`.
 This endpoint receives the target project ID, but the commitment ID from the source project.
 Requires a generated token from the API: `/v1/domains/:id/projects/:id/commitments/:id/start-transfer`.
 On success the API clears the `transfer_token` and `transfer_status` from the commitment.