--extend switch not listed in Command Details

[dshaw619]

The Command Details Wiki page (https://github.com/gitbls/sdm/wiki/Command-Details) does not document --extend as a switch to --customize. When --customize failed for lack of space, I got the message "% If needed use --extend --xmb nnnn with --customize to create more space".

[gitbls]

Updated that wiki page to reflect that --extend can be used with --customize.

Thanks!