minor changes to documentation page

html/documentation.html

@@ -55,10 +55,10 @@ description: Quick access to the documentation of Frama-C and the plugins develo
 
           <div class="tileWrapper" size="small">
             <div class="tileWrapperTitle">
-              <span>Plug-in Manuals</span>
+              <span>Plug-ins</span>
             </div>
             <div class="tile">
-              <h4 class="tileTitle"><span>Plugin Development</span></h4>
+              <h4 class="tileTitle"><span><i>Plug-in Development</i></span></h4>
               <ul>
                 <li><a href="/download/frama-c-plugin-development-guide.pdf">Developer manual</a></li>
               </ul>