[PATCH] README: various updates

[Eric Wong <e@80x24.org>]

We no longer scrub content, and instead reject things by
default.  Further reduce mentions of ssoma and minor formatting
tweaks.
---
 README | 38 ++++++++++++++++++--------------------
 1 file changed, 18 insertions(+), 20 deletions(-)

diff --git a/README b/README
index e8555aa..a91c45b 100644
--- a/README
+++ b/README
@@ -22,33 +22,31 @@ to run their own instances with minimal overhead.
 Implementation
 --------------
 
-public-inbox uses ssoma[1], Some Sort Of Mail Archiver which implements
-no policy of its own.  By storing (and optionally) exposing an inbox
-via git, it is fast and efficient to host and mirror public-inboxes.
+public-inbox stores mail in a git repository keyed by Message-ID
+as documented in: https://ssoma.public-inbox.org/ssoma_repository.txt
 
-Traditional mailing lists use the "push" model.  For readers, this
-requires commitment to subscribe and effort to unsubscribe.  New readers
-may also have difficulty following existing discussions if archives do
-not expose Message-ID headers for responses.  List server admins may be
-burdened with delivery failures.
+By storing (and optionally) exposing an inbox via git, it is
+fast and efficient to host and mirror public-inboxes.
 
-public-inbox uses the "pull" model.  Casual readers may also follow
-the list via NNTP, Atom feed or HTML archives.
+Traditional mailing lists use the "push" model.  For readers,
+that requires commitment to subscribe and effort to unsubscribe.
+New readers may also have difficulty following existing
+discussions if archives do not expose Message-ID and References
+headers.  List server admins are also burdened with delivery
+failures.
 
-Users of the ssoma[1] command-line tool may import mail into an mbox,
-Maildir, or IMAP folder from git repositories periodically.
+public-inbox uses the "pull" model.  Casual readers may also
+follow the list via NNTP, Atom feed or HTML archives.
 
 If a reader loses interest, they simply stop syncing.
 
 Since we use git, mirrors are easy-to-setup, and lists are
-easy-to-relocate to different mail addresses without losing/splitting
-archives.
+easy-to-relocate to different mail addresses without losing
+or splitting archives.
 
 _Anybody_ may also setup a delivery-only mailing list server to
 replay a public-inbox git archive to subscribers via SMTP.
 
-[1] https://ssoma.public-inbox.org/
-
 Features
 --------
 
@@ -133,10 +131,10 @@ See https://public-inbox.org/dc-dlvr-spam-flow.html for more info.
 Content Filtering
 -----------------
 
-To discourage phishing, web bugs (tracking), viruses and other nuisances,
-only plain-text content is allowed and non-text content is stripped.
-This saves I/O bandwidth and storage, which is important as
-entire mail archives are shared between clients.
+To discourage phishing, trackers, exploits and other nuisances,
+only plain-text emails are allowed and HTML is rejected.
+This improves accessibility, and saves bandwidth and storage
+as mail is archived forever.
 
 As of the 2010s, successful online social networks and forums are the
 ones which heavily restrict users formatting options; so public-inbox