language-matrix, added note about clicking on cells for more detail

gap-analysis/language-matrix.html

@@ -106,7 +106,7 @@ <h2>Results:</h2>
     <p><strong><span style="background-color:white; border:1px solid gray;">?</span> <span id="unknown"></span></strong> of cells still need investigation.</p>
   </div>
 </div>
-<p>&nbsp;</p>
+<p>If a language has a link, click on any cell in that row to see more detail about why the cell was scored that way.</p>
 <table id="results">
   <thead>
     <tr id="table_headers">