Clean up minor inconsistency re public disclosure

Clean up minor inconsistency re public disclosure

Include a summary of both kinds of e-mail which may be sent to the
pre-disclosure list in the "Pre-disclosure list" section, before the
discussion of what is expected of pre-disclosure list members.  Also
make it consistently clear that the public disclosure will always be
sent to the pre-disclosure list.

Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com>