doc: Add troubleshooting

docs/_layouts/default.html

@@ -39,6 +39,7 @@ <h1>Guide</h1>
       <li><a href='./search_engines.html'>Search engines</a></li>
       <li><a href='./properties.html'>Properties</a></li>
       <li><a href='./styles.html'>Custom Styles</a></li>
+      <li><a href='./troubleshooting.html'>Troubleshooting</a></li>
     </ul>
   </aside>
 
@@ -55,6 +56,7 @@ <h1>Guide</h1>
       <li><a href='./search_engines.html'>Search engines</a></li>
       <li><a href='./properties.html'>Properties</a></li>
       <li><a href='./styles.html'>Custom Styles</a></li>
+      <li><a href='./troubleshooting.html'>Troubleshooting</a></li>
       <li class='separator'></li>
       <li><a target="_blank" rel="noopener" href='https://github.com/ueokande/vimmatic'>GitHub</a></li>
       <li><a target="_blank" rel="noopener" href='https://addons.mozilla.org/firefox/addon/vimmatic/'>Firefox Add-ons</a></li>

docs/troubleshooting.md

@@ -0,0 +1,39 @@
+---
+title: Troubleshooting
+---
+
+# Troubleshooting
+
+## The addon is not working on the Firefox
+
+The firefox addon with Manifest V3 requires optional permissions to work well
+on any website. You can find it on `Permissions` section of `Vimmatic` settings
+on the `about:addons` page.  Please make sure that the `Access your data for
+all websites` is enabled.
+
+![Access your data for all websites is enables](./assets/images/Access_your_data_for_all_websites.png)
+
+## Url tooltip is hiding the console
+
+When them mouse cursor hovers over a link, a tooltip shows up in the bottom of
+the screen.  It can hide the console of the addon.  You can remove this tooltip
+by adding custom styles into `userChrome.css` file.  Please follow the steps
+below:
+
+1. Enable the `toolkit.legacyUserProfileCustomizations.stylesheets` option in
+   the `about:config` page.
+2. Create `userChrome.css` file in the `chrome` directory under the profile
+   directory.  The location of the `userChrome.css` should be `<profile
+   directory>/chrome/userChrome.css`.  You can find the location of the profile
+   directory at the `Profile Directory` section on the `about:support` page.
+3. Add the following content into the `userChrome.css` file:
+
+   ```css
+   @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
+
+   #statuspanel {
+     display: none !important;
+   }
+   ```
+
+4. Restart the browser.