Exception implements Throwable

While this is only the case as of PHP 7.0.0, we nonetheless make it
the default, and change the note regarding the former state.

Based on a patch provided by Artem Ostretsov.

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@345149 c90b9560-bf6c-de11-be94-00142212c4b1

language/predefined/exception.xml

@@ -20,7 +20,7 @@
     7.
    </para>
    <para>
-    In PHP 7, <classname>Exception</classname> implements the
+    Before PHP 7, <classname>Exception</classname> did not implement the
     <classname>Throwable</classname> interface.
    </para>
   </section>
@@ -38,6 +38,11 @@
      <ooclass>
       <classname>Exception</classname>
      </ooclass>
+
+     <ooclass>
+      <modifier>implements</modifier>
+      <classname>Throwable</classname>
+     </ooclass>
     </classsynopsisinfo>
 <!-- }}} -->