Updated links to Liberation Font resources

Author: himorin

imsc1/spec/ttml-ww-profiles.html

@@ -4208,7 +4208,7 @@ <h2>Reference Fonts</h2>
 
           <td>
             <a href="https://docs.microsoft.com/en-us/typography/font-list/courier-new">Courier New</a> or <a href=
-            "https://fedorahosted.org/liberation-fonts/">Liberation Mono</a>
+            "https://github.com/liberationfonts/liberation-fonts">Liberation Mono</a>
           </td>
         </tr>
 
@@ -4223,7 +4223,7 @@ <h2>Reference Fonts</h2>
           <td>
             <a href="https://docs.microsoft.com/en-us/typography/font-list/arial">Arial</a> or <a href=
             "https://www.linotype.com/1308886/helvetica-family.html">Helvetica</a> or <a href=
-            "https://fedorahosted.org/liberation-fonts/">Liberation Sans</a>
+            "https://github.com/liberationfonts/liberation-fonts">Liberation Sans</a>
           </td>
         </tr>
       </tbody>