Fixes #13400, #13415: actually document the existing practice for links in panel headings

docs/_includes/components/panels.html

@@ -22,6 +22,7 @@
 
   <h3 id="panels-heading">Panel with heading</h3>
   <p>Easily add a heading container to your panel with <code>.panel-heading</code>. You may also include any <code>&lt;h1&gt;</code>-<code>&lt;h6&gt;</code> with a <code>.panel-title</code> class to add a pre-styled heading.</p>
+  <p>For proper link coloring, be sure to place links in headings within <code>.panel-title</code>.</p>
   <div class="bs-example">
     <div class="panel panel-default">
       <div class="panel-heading">Panel heading without title</div>