Add go top of page link to major sections

Per [issure 283](#283),
add a link to each major section of the about page which allows the user
to move to the index of topics at the top of the page.

public_html/css/hpr.css

@@ -371,6 +371,9 @@ article > p,
 	font-size: 1.45rem;
 	color: var(--background-primary);
 }
+.lane > article > header > .index-link {
+	float: right;
+}
 .lane.stack > article  {
 	border-radius: 0.5rem;
 	border: thin solid var(--background-secondary);