Add info to style_chmduquesne.css

Add references to the css stylesheet which mention what the
corresponding variables are called in the ConTeXt version.

style_chmduquesne.css

@@ -32,6 +32,7 @@ h1:hover {
 
 /* Titles of categories */
 h2 {
+    /* This is called "sectioncolor" in the ConTeXt stylesheet. */
     color: #397249;
 }
 /* There is a bar just before each category */
@@ -41,6 +42,7 @@ h2:before {
     margin-right:1%;
     width: 16%;
     height: 10px;
+    /* This is called "rulecolor" in the ConTeXt stylesheet. */
     background-color: #9CB770;
 }
 h2:hover {