security: highlight phab accounts; recommend phab for nominations

This commit contains two mildly separate concepts.

First, sending out reviews for things like this is a bit of a
complicated endeavor, since the reviewer list is relatively long, and I
generally rely on prior CLs in this area to find an authoritative list.
Life's quite a bit easier if phab usernames are readily available on the
doc. So part 1 is making those available.

Second, it seems to me that, at the moment, Phabricator makes the most
sense for membership changes (incl. security group nominations). My
reasoning for this is detailed in the diff, and to some extent in
comment #1 of this bug
<https://bugs.chromium.org/p/llvm/issues/detail?id=12#c1>. This change
adds prose to recommend the use of Phabricator for nominations as a
result.

Differential Revision: https://reviews.llvm.org/D106917

llvm/docs/Security.rst

@@ -31,24 +31,24 @@ Group Composition
 Security Group Members
 ----------------------
 
-The members of the group represent a wide cross-section of the community, and meet the criteria for inclusion below.
-
-* Ahmed Bougacha (Apple)
-* Artur Pilipenko (Azul Systems Inc)
-* Dimitry Andric (individual; FreeBSD)
-* Ed Maste (individual; FreeBSD)
-* George Burgess IV (Google)
-* Josh Eads (Sony)
-* Kate McInnes (Apple)
-* Kristof Beyls (ARM)
-* Matthew Riley (Google)
-* Oliver Hunt (Apple)
-* Paul Robinson (Sony)
-* Peter Smith (ARM)
-* Pietro Albini (individual; Rust)
-* Serge Guelton (RedHat)
-* Shayne Hiet-Block (Microsoft)
-* Steve Klabnik (Oxide Computer Company; Rust)
+The members of the group represent a wide cross-section of the community, and meet the criteria for inclusion below. The list is in the format `* ${full_name} (${affiliation}) [${phabricator_username}]`. If a phabricator username for an individual isn't available, the brackets will be empty.
+
+* Ahmed Bougacha (Apple) [ab]
+* Artur Pilipenko (Azul Systems Inc) [apilipenko]
+* Dimitry Andric (individual; FreeBSD) [dim]
+* Ed Maste (individual; FreeBSD) [emaste]
+* George Burgess IV (Google) [george.burgess.iv]
+* Josh Eads (Sony) []
+* Kate McInnes (Apple) []
+* Kristof Beyls (ARM) [kristof.beyls]
+* Matthew Riley (Google) [mattdr]
+* Oliver Hunt (Apple) [ojhunt]
+* Paul Robinson (Sony) [probinson]
+* Peter Smith (ARM) [peter.smith]
+* Pietro Albini (individual; Rust) [pietroalbini]
+* Serge Guelton (RedHat) [serge-sans-paille]
+* Shayne Hiet-Block (Microsoft) [Shayne]
+* Steve Klabnik (Oxide Computer Company; Rust) [steveklabnik]
 
 Criteria
 --------
@@ -85,8 +85,9 @@ Nomination process
 
 Anyone who feels they meet these criteria can nominate themselves, or may be nominated by a third party such as an existing LLVM Security Group member. The nomination should state whether the nominee is nominated as an individual, researcher, or as a vendor contact. It should clearly describe the grounds for nomination.
 
-*FUTURE*: where nomination occurs (mailing list, GitHub, etc), can be decided later. See `Discussion Medium`_ below.
+For the moment, nominations are generally proposed, discussed, and voted on using Phabricator. An `example nomination is available here`_. The use of Phabricator helps keep membership discussions open, transparent, and easily accessible to LLVM developers in many ways. If, for any reason, a fully-world-readable nomination seems inappropriate, you may `open a new issue`_, and a discussion can be had about the best way to approach nomination, given the constraints that individuals are under.
 
+Our recommended method of nomination may change as our `Discussion Medium`_ story evolves over time.
 
 Choosing new members
 --------------------
@@ -226,3 +227,4 @@ The parts of the LLVM Project which are currently treated as non-security sensit
 .. _GitHub security: https://help.github.com/en/articles/about-maintainer-security-advisories
 .. _llvm-dev mailing list: https://lists.llvm.org/mailman/listinfo/llvm-dev
 .. _MITRE: https://cve.mitre.org
+.. _example nomination is available here: https://reviews.llvm.org/D99232