Clarify key info about "wide links" setting

[github at samba.org]

New comment by douglasbagnall on Samba Github repository

https://github.com/samba-team/samba/pull/141#issuecomment-451053389
Comment:
@stilez: this looks good to me, though I know nothing about wide links. To get the attention of people who do, the best approach would be to squash the four commits together and add a "Signed-off-by:' line, then send the patch to the Samba technical list (https://lists.samba.org/mailman/listinfo/samba-technical), or open a Samba bugzilla bug report or a merge request on https://gitlab.com/samba-team/samba/.