Remove ArgumentNullException from IPAddress.TryParse docs (dotnet#10629)

Author: MihaZupan

xml/System.Net/IPAddress.xml

@@ -2709,8 +2709,6 @@
 
  ]]></format>
         </remarks>
-        <exception cref="T:System.ArgumentNullException">
-          <paramref name="ipString" /> is <see langword="null" />.</exception>
       </Docs>
     </Member>
     <Member MemberName="TryParse">