pluralize the works covered by the cc-by-sa license

index.html

@@ -288,7 +288,7 @@
               <br />
               <p><a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/80x15.png" /></a>
               <br />
-              This work by <a xmlns:cc="http://creativecommons.org/ns#" href="http://open.edx.org" property="cc:attributionName" rel="cc:attributionURL">edX Inc.</a> is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">Creative Commons Attribution-ShareAlike 4.0 International License</a>.</p>
+              These works by <a xmlns:cc="http://creativecommons.org/ns#" href="http://open.edx.org" property="cc:attributionName" rel="cc:attributionURL">edX Inc.</a> are licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">Creative Commons Attribution-ShareAlike 4.0 International License</a>.</p>
             </div>
           </div>
         </aside>