Update with the members of the 11th core team, core.xi

• Update en_US.ISO8859-1/articles/contributors/contrib.corealumni.xml to reflect outgoing CORE.10 members
• Update en_US.ISO8859-1/books/dev-model/book.xml to reflect changes in core-secretary@
• Update en_US.ISO8859-1/books/handbook/introduction/chapter.xml to reflect changes on latest Election Date
• Update en_US.ISO8859-1/htdocs/administration.xml to reflect latest CORE.11 team and respective Liason
• Update share/pgpkeys/pgpkeys-core.xml to reflect CORE.11 members
• Update share/pgpkeys/core-secretary.key signed by outgoing core-secretary@ and jrm@
• gpg --list-key --fingerprint core-secretary@freebsd.org

pub rsa4096 2020-06-26 [SC] [expires: 2022-06-30]

4B64 E9E0 BDE9 B3EC C06B 5C66 D8C8 C83B 49F2 6F17

uid [ultimate] FreeBSD Core Team Secretary <core-secretary@freebsd.org>
sig 3 D8C8C83B49F26F17 2020-06-26 FreeBSD Core Team Secretary <core-secretary@freebsd.org>
sig 36A40C83B0D6EF9E 2020-06-26 Joseph R. Mingrone <jrm@ftfl.ca>
sig 0CB403E4E95B96EC 2020-06-26 [User ID not found]
sub rsa4096 2020-06-26 [E] [expires: 2022-06-30]
sig D8C8C83B49F26F17 2020-06-26 FreeBSD Core Team Secretary <core-secretary@freebsd.org>

Submitted by: bofh (with core-secretary@ hat on)
Approved by: bcr, jrm
Differential Revision: https://reviews.freebsd.org/D25527