fix learning link (#2823)

Signed-off-by: Arhell <arhell333@gmail.com>

Author: Arhell

docs/themes/porter/layouts/partials/nav.html

@@ -2,6 +2,6 @@
 <li><a href="/quickstart" title="Try Porter">QuickStart</a></li>
 <li><a href="/blog" title="Blog">Blog</a></li>
 <li><a href="/community" title="Connect with Other Users">Community</a></li>
-<li><a href="/learning" title="Videos and Tutorials">Learning</a></li>
+<li><a href="/learn/learning/" title="Videos and Tutorials">Learning</a></li>
 <li><a href="/docs" title="Porter Documentation">Docs</a></li>
 <li><a href="https://github.com/getporter/porter" target="_blank" title="Porter on Github"><img src="{{ .Site.BaseURL }}img/github.svg" alt="Github" /></a></li>