fix: Don't include modal headings in right-hand nav menu (ietf-tools#5710)

Fixes ietf-tools#5701

Author: larseggert

ietf/static/js/ietf.js

@@ -155,7 +155,7 @@ $(function () {
         const heading_selector = ":is(h2, h3, h4, h5, h6, .h2, .h3, .h4, .h5, .h6, .nav-heading):not([style='display:none']):not(.navskip)";
         const headings = contentElement
             .find(heading_selector)
-            .filter((i, el) => !el.closest(".navskip"));
+            .filter((i, el) => !el.closest(".navskip,.modal"));
 
         const contents = (headings.length > 0) &&
             ($(headings)