doc: quote list items in POD

Recent versions of Pod::Simple complain if we use integers or other
special characters in an =item list. We have a couple bulleted lists
that happen to have integers or other special characters as the list
values. Quote the items with C<> so that Pod::Simple can correctly parse
them again.

Change-Id: If456781fe219b73ae01feb9aef2fb2639e097534
Reviewed-on: http://gerrit.openafs.org/9838
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>