#4237 Document the use of site.managedaddressmode

[Lissa Valletta]

Please add to the appropriate the document the use of the site.managedaddressmode attribute. What does it do and after you set it what you need to do. I only found it in Schema.pm, not in any of our docs. Also update any manpages if necessary.

[Lissa Valletta]

This can be fixed later.

[yangsong]

add the document in https://sourceforge.net/p/xcat/wiki/Enabling%20the%20unicast%20dhcp%20during%20node%20provisioning/