Use a public mailing list for predisclosure membership applications.

Use a public mailing list for predisclosure membership applications.

IMPLEMENTATION TASKS:
 * Create the mailing list (and check that it works from outside)

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
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v2: Provide whole email address for predisclosure-applications@,
    but obfuscate it with <dot> and a <span>.
    Reword sentence about public mailing list as suggested by
    Ian Campbell.