Added TODO for descriptorVersion parameter

The descriptorVersion parameter is not public API, but it makes sense
to make the parameter of type string and create a SemVer object inside.

lib/processors/manifestCreator.js

@@ -652,7 +652,7 @@ async function createManifest(libraryResource, libBundle, descriptorVersion, _in
 module.exports = function({libraryResource, resources, options}) {
 	// merge options with defaults
 	options = Object.assign({
-		descriptorVersion: APP_DESCRIPTOR_V22,
+		descriptorVersion: APP_DESCRIPTOR_V22, // TODO change this to type string instead of a semver object
 		include3rdParty: true,
 		prettyPrint: true
 	}, options);