Define session.UnsubscribeParameters to match other commands (#866)

Author: OrKoN

index.bs

@@ -2085,8 +2085,10 @@ and will be removed in the future versions.
      <pre class="cddl remote-cddl">
      session.Unsubscribe = (
        method: "session.unsubscribe",
-       params: session.UnsubscribeByAttributesRequest / session.UnsubscribeByIDRequest,
+       params: session.UnsubscribeParameters,
      )
+
+     session.UnsubscribeParameters = session.UnsubscribeByAttributesRequest / session.UnsubscribeByIDRequest
      </pre>
    </dd>
    <dt>Result Type</dt>