Fix variable name casing for versionId

Author: rkunjappan

js/source/preview.js

@@ -3,7 +3,7 @@ import {ARTICLE_UPDATE_SUBSCRIPTION, PantheonClient, PublishingLevel} from "@pan
 const params = new URLSearchParams(window.location.search);
 const documentId = drupalSettings.path.currentPath.split('/')[3];
 const publishingLevelParam = params.get('publishingLevel');
-const VersionId = params.get('versionId');
+const versionId = params.get('versionId');
 
 const pantheonClient = new PantheonClient({
     siteId: window.drupalSettings.pantheon_content_publisher.site_id,