links to plugin authoring page added and fixed (#4822)

* links to plugin authoring page fixed

Do I use html hyperlinks in the .js file? Happy to change that if needed.

* correct .js file and corrected link

* deleted packages.js~HEAD and updated link to plugin authoring

* Fix link

Author: shannonbux

docs/docs/plugins.md

@@ -12,7 +12,7 @@ into site-specific plugins.
 Gatsby has a large and growing set of plugins. To search/browse official and
 community plugins and their documentation, visit the [Plugin Library](/packages/).
 
-For information on building your own plugin, see the Plugin Authoring page (/plugin-authoring.md).
+For information on building your own plugin, see the [Plugin Authoring page](/docs/plugin-authoring/).
 
 ## How to use Gatsby plugins?
 

www/src/pages/packages.js~HEAD

@@ -53,7 +53,8 @@ class Plugins extends Component {
             }}
           >
             Please use the search bar to find plugins that will make your
-            blazing-fast site even more awesome.
+            blazing-fast site even more awesome. If you'd like to create your own plugin,
+            see the <Link to="/docs/plugin-authoring/">Plugin Authoring</Link> page in the docs!
           </p>
         </div>
       </Container>