migration84: Improve phrasing of the E_STRICT removal (#3917)

Author: TimWolla

appendices/migration84/incompatible.xml

@@ -83,7 +83,7 @@
    <simpara>
     The <constant>E_STRICT</constant> error level has been removed,
     as it was no longer in use within the PHP engine.
-    The <constant>E_STRICT</constant> has also been deprecated.
+    The <constant>E_STRICT</constant> constant has been deprecated.
    </simpara>
   </sect3>
  </sect2>