README.md in postfix-exporter-2.0.3 vs README.md in postfix-exporter-2.1.0

@@ -5,22 +5,37 @@
 # Features
 
 * Examines mail queue periodically and exports `postfix_mail_queue_size`;
 
 * Reads syslog entries as they happen, and exports disposition status
-  counters (`postfix_disposition`) per DSN, as well as delay summaries per
-  DSN;
+  counters (`postfix_delivery_delays_count`) per DSN, as well as delay summaries per
+  DSN (`postfix_delivery_delays{quantile="..."}`);
 
+* Total number of SMTP connections (`postfix_smtpd_connections_total`) and
+  currently-active connections (`postfix_smtpd_active_connections`);
+
+* Count how many delivery attempts were received
+  (`postfix_incoming_delivery_attempts_total`), split out by whether we
+  accepted or rejected the message (`status`) and the exact DSN provided to
+  the client (`dsn`);
+
+* Whether or not the Postfix `master` process is running (`postfix_up`);
+
 * Drinks from the syslog stream directly.
 
 
 # Deployment
 
 The default way of rolling out this exporter is as a Docker container.  For
 that, you'll want to setup a volume for the postfix queue (making it
 available in the container as `/var/spool/postfix`), and some env
 vars.  You can also run it directly (via the gem), with the same env vars,
 and with the expectation that `/var/spool/postfix` is in the usual place.
+
+If you configure the postfix-exporter to run in the same PID namespace as
+whatever it is that's running Postfix itself (either `--pid=host` or in the
+same NS namespace, a la k8s pods), then the `postfix_up` metric will be
+valid, otherwise it'll be random (but unlikely to be correct).
 
 
 ## Environment Variables
 
 * `SYSLOG_SOCKET` -- where to read raw syslog events from.  If you're