Add javascript comments to the dt-ids snippet

Author: neon-ninja

_includes/javascript.html

@@ -13,15 +13,21 @@
   ga('send', 'pageview');
 </script>
 <script>
+  // This snippet fixes a bug caused by Github's pages-gem using kramdown v1.11.1.
+  // In order for anchor links to point to the correct place in the glossary, they must have an id
+  // This snippet ensures every definition term has an id
+  // See https://github.com/swcarpentry/styles/pull/129
   $('dt').each(function () {
     if (!this.id) {
       var id = $(this).text();
+      // If there's a ( in the name (e.g., "comma-separated values (CSV)") - just take everything up to the first (
       var index = id.indexOf('(');
       if (index > 0) {
         id = id.substring(0, index);
       }
+      // Strip leading and trailing whitespace, convert spaces to dashes and convert everything to lowercase
       id = id.trim().replace(/ /g, '-').toLowerCase();
       this.id = id;
     }
   });
-</script>
+</script>