Create nav.html

Author: Someshdiwan

site/_includes/nav.html

@@ -0,0 +1,9 @@
+<h2>📘 Navigation</h2>
+<nav>
+  <ul>
+    <li><a href="{{ '/' | relative_url }}">Home</a></li>
+    <li><a href="{{ '/Explaination' | relative_url }}">Explaination</a></li>
+    <li><a href="{{ '/content' | relative_url }}">All Contents</a></li>
+    <li><a href="https://github.com/Someshdiwan/JavaEvolution-Learning-Growing-Mastering">GitHub Repo</a></li>
+  </ul>
+</nav>