new option to replace current tab when a assigned domain is opened

src/options.html

@@ -20,6 +20,13 @@
         Enable Sync
       </label>
       <p><em>This setting allows you to sync your containers and site assignments across devices.</em></p>
+      <h3>Tab behaviour:</h3>
+      <label>
+        <input type="checkbox" id="replaceTabCheck">
+        Enable tab replace for assigned domains
+      </label>
+      <p><em>Replace current tab if a page which is assigned to a specific container is opened (instead of keeping the current tab open).
+        Opening tabs with middle mouse button is not affected.</em></p>
       <h3>Keyboard Shortcuts:</h3>
       <p><em>Edit which container is opened when using the numbered shortcuts.</em></p>
       <p><label>