Document Wordpress security issues in 4.7.1.

Note per upstream PHPMailer was updated but "No specific issue appears
to affect WordPress or any of the major plugins we investigated". As such
leave the PHPMailer entry as is at this time.

PR: 216059
Reported by: Jochen Neumeister <joneum@bsdproject.de>
Security: CVE-2017-5487
Security: CVE-2017-5488
Security: CVE-2017-5489
Security: CVE-2017-5490
Security: CVE-2017-5491
Security: CVE-2017-5492
Security: CVE-2017-5493
Security: https://vuxml.FreeBSD.org/freebsd/b180d1fb-dac6-11e6-ae1b-002590263bf5.html