Add a file server example (#8)

Added an example of a prim-dns file server setup, with more intricate pages that make use of other files (like including a Javascript script) and dynamic responses (getting a list of agents in the region).

file server/example/javascript/index.js

@@ -0,0 +1,5 @@
+window.addEventListener('load', function() {
+    document.querySelectorAll('.color-button').forEach(btn => btn.addEventListener('click', function() {
+        document.getElementById('color-text').style.color = btn.getAttribute('data-color');
+    }));
+});