Use M_CONSENT_NOT_GIVEN
No idea where I got the other one from: we already have one in the
spec, so use it.
@@ -190,7 +190,7 @@ may return:
* `M_UNAUTHORIZED` errcode with HTTP status code 401. This indicates that
the user must authenticate with OpenID and supply a valid `access_token`.
- * `M_TERMS_NOT_SIGNED` errcode. This indicates that the user must agree to
+ * `M_CONSENT_NOT_GIVEN` errcode. This indicates that the user must agree to
(new) terms in order to use or continue to use the service.
The `_matrix/identity/v2/3pid/unbind` must not return either of these
