[PATCH] README: update and add more URLs for archives

[Eric Wong]

public-inbox.org now runs an anonymous IMAP server
(AUTH=ANONYMOUS is also supported).  If we ever exceed 50000K
messages in our mail archives, new messages will appear in the
".1" mailbox.

Tor .onion URLs have always been supported, too.

news.gmane.org also moved to news.gmane.io a while back:

https://lars.ingebrigtsen.no/2020/01/15/news-gmane-org-is-now-news-gmane-io/
---
 README | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/README b/README
index 378d8e2..562045a 100644
--- a/README
+++ b/README
@@ -82,8 +82,13 @@ Mailing list archives available at 
<https://80x24.org/dtas-all/> or
 No subscription is necessary to post to the mailing list.
 You may also read via:
 NNTP: <nntp://news.public-inbox.org/inbox.comp.audio.dtas>
-       <nntp://news.gmane.org/gmane.comp.audio.dtas.general>
+       <nntp://ou63pmih66umazou.onion/inbox.comp.audio.dtas>
+       <nntp://news.gmane.io/gmane.comp.audio.dtas.general>
+IMAP: <imaps://anon:mous@public-inbox.org/inbox.comp.audio.dtas.0>
+       <imap://anon:mous@ou63pmih66umazou.onion/inbox.comp.audio.dtas.0>
 Atom: <https://80x24.org/dtas-all/new.atom>
+       <http://ou63pmih66umazou.onion/dtas-all/new.atom>
+(.onion URLs require Tor: <https://www.torproject.org/>)
 
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