Manual - survey

Possible wording for the survey bit
Is this the right place to put it?
Will probably need an image, but that would be better from Willem's
environment for the look to be consistent.

Signed-off-by: Tim Wootton <tim@tee-jay.demon.co.uk>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

Documentation/user-manual.txt

@@ -1,4 +1,4 @@
-// Subsurface 4.1 User Manual
+// Subsurface 4.2 User Manual
 // ==========================
 // :author: Manual authors: Jacco van Koll, Dirk Hohndel, Reinout Hoornweg,
 // Linus Torvalds, Miika Turkia, Amit Chaudhuri, Jan Schubert, Willem
@@ -56,6 +56,17 @@ included with the source code.
 *Audience*: Recreational Scuba Divers, Free Divers, Tec Divers, Professional
 Divers
 
+After using _Subsurface_ for a week or so, a one-box survey will pop up when
+you launch the program. The survey is entirely optional, you control what, if
+any, data is sent to the _Subsurface_ team. Any data that you choose to send
+will be very welcome, and will only be used to steer future development
+effort and direction. If you carry out the survey, or click the option not to
+be asked again, that should be the last time you'll be bothered by the pop-up,
+but if your diving and/or subsurface habbits change and you wish to provide
+another survey you can do this by launching _Subsurface_ with --survey on the
+command line.
+
+
 toc::[]
 
 [[S_StartUsing]]