new committer (src): Pierre Pronchery (khorben)

[khorben_defora.org]

Summary

per the committer's guide for new committers:

• add my pgp key
• add myself to shared/authors.adoc
• remove myself from shared/contrib-additional.adoc
• add myself to shared/contrib-committers.adoc
• add a news entry

[khorben_defora.org]

Reflect the new expiration date for the PGP/GPG key, after passing the documentation/tools/checkkey.sh test.

[khorben_defora.org]

Since I am not a doc committer, I have pushed a copy of this commit at https://github.com/khorben/freebsd-doc/tree/khorben/new-committer for convenience.

[philip]

Approved by: philip (mentor)

You can commit to the doc repo without further approval (I'm also a doc committer :-))