Update broken link, remove double link in F47 (#3701)

MDN no longer has a page on the blink element, replacing it with a link
to Wikipedia for historical reference.

The second link went to the same place, also removed that as it was
redundant.

techniques/failures/F47.html

@@ -25,12 +25,9 @@
 
          <ul>
             <li> 
-                  <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/blink">Mozilla Developer Network: &lt;blink&gt;</a> 
-               </li>
-            <li> 
-                  <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/blink">Mozilla Developer Network: text-decoration</a> 
+                  <a href="https://en.wikipedia.org/wiki/Blink_element">Wikipedia: Blink element</a> 
                </li>
          </ul>
 
    </section>
-</body></html>
+</body></html>