explain why 1.2.2 of commons-net is recommended.

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@276660 13f79535-47bb-0310-9956-ffa450edef68

docs/manual/install.html

@@ -403,7 +403,8 @@ you need jakarta-oro 2.0.1 or later, and <a href="#commons-net">commons-net</a><
     <td><a name="commons-net">commons-net.jar</td>
     <td>ftp, rexec and telnet tasks<br>
     jakarta-oro 2.0.1 or later is required in any case together with commons-net.<br>
-    For all users, a minimum version of commons-net of 1.2.2 is recommended.
+    For all users, a minimum version of commons-net of 1.2.2 is recommended.  Earlier 
+    versions did not support autodetection of system type or had significant bugs.
     </td>
     <td><a href="http://jakarta.apache.org/commons/net/index.html"
            target="_top">http://jakarta.apache.org/commons/net/index.html</a></td>