update README and add a screenshot

README

@@ -1,8 +1,21 @@
 TTS - Time-tracking software
 ============================
 
-TTS is a simple, text-based (curses) time-tracking application.  For more
-details, see the website at <http://loreley.flyingparchment.org.uk/~felicity/pages/tts>.
+TTS is a simple, text-based (curses) time-tracking application.  It allows you
+to track the time you spend working by client, project, etc. to allow accurate
+invoicing of clients or reporting to a corporate time-tracking system.  It
+uses a simple text format to store data which can easily be parsed to export
+data to another system automatically.  Entries can be added in bulk or in real
+time using a timer, and invoiced and non-billable entries are tracked.
+Entries can optionally be rounded up to a minimum billing increment.
+
+Screenshot
+----------
+
+![A screenshot of TTS in use](screenshot.png)
+
+Installation
+------------
 
 TTS has been tested on FreeBSD, NetBSD, Solaris, Cygwin and Linux, with the
 following caveats:
@@ -21,7 +34,8 @@ TTS uses autoconf and can be built as follows:
 
 After starting with 'tts', type '?' for help.
 
-### Quick start:
+Quick start
+-----------
 
 * Press 'a' to add a new entry, and enter its name.  The timer starts running.
 * Press space to toggle the timer on and off.
@@ -34,12 +48,9 @@ After starting with 'tts', type '?' for help.
   start the interrupt timer.  When you're done with the other thing, press 'r'
   again to assign the interrupt time to a new entry.
 
-### Contact
+Contact
+-------
 
-There is a mailing list for TTS users.  To subscribe to it, send mail to 
-<listserv@lists.le-fay.org> with "subscribe tts" in the body.  Announcements of 
-new releases and important changes will be posted to this list.
-
-Alternatively, to report problems or request features, use the GitHub issue 
-tracker at <https://github.com/ftarnell/tts/issues>.  This requires that you 
-have a GitHub account
+To report problems or request features, please use the GitHub issue tracker at
+<https://github.com/ftarnell/tts/issues>.  This requires that you have a GitHub
+account.