doc: Clarify some BosConfig.new text

doc: Clarify some BosConfig.new text

It is not always clear to users whether BosConfig.new is noticed
during an automatic restart, or if it requires stopping and starting
the bosserver. Slightly reword the relevant text and add a small note
that a "general restart" does cause BosConfig.new to be noticed, so
this is explicitly clear.

Change-Id: Iab3eaff176305b0b2991a6636e70204b5072b1b0
Reviewed-on: http://gerrit.openafs.org/11076
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>