refactor(workflows): generate workflow manager via HtmlWebpackPlugin

Change-Id: I50a6aba661bee2fabd634b6bf13d4a60459acc14
diff --git a/src/bg.js b/src/bg.js
index fce2328..789be62 100644
--- a/src/bg.js
+++ b/src/bg.js
@@ -109,7 +109,7 @@
 
     case 'openWorkflowsManager':
       chrome.tabs.create({
-        url: chrome.runtime.getURL('options/workflows.html'),
+        url: chrome.runtime.getURL('workflows.html'),
       });
       break;