Add mention of the commented out gphoto2 entry in dll.conf

doc/sane-gphoto2.man

@@ -7,8 +7,13 @@ The
 .B sane-gphoto2
 library implements a SANE (Scanner Access Now Easy) backend that
 provides access to the digital cameras supported by gphoto2. 
-THIS IS EXTREMELY ALPHA
-CODE!  USE AT YOUR OWN RISK!!
+This backend has only been tested with a handful of cameras so far.  Patches
+to support other models are welcome.
+.PP
+Because of the limited testing of this backend, it is commented out
+in @CONFIGDIR@/dll.conf by default.  Either the comment
+character must be removed or the backend must be called explicitly.
+E.g. `scanimage -d gphoto2' or `xscanimage gphoto2'.
 .SH "DEVICE NAMES"
 The current version of the backend only allows one camera to be
 connected.  The device name is always "0".
@@ -88,6 +93,10 @@ If the library was compiled with debugging support enabled, this
 environment variable controls the debug level for this backend. 
 A value of 128 requests maximally copious debug output; smaller
 levels reduce verbosity.
+.TP 
+.B GP_DEBUG
+Set to 1, 2, or 3, to enable various levels of debugging within the 
+gphoto2 libraries.
 
 .SH "SEE ALSO"
 sane(7)
@@ -99,7 +108,7 @@ Peter S. Fales
 The manpage was largeley copied from the dc210 manpage.
 
 .SH BUGS
-Many.
+Many, no doubt.
 .PP
 More general comments, suggestions, and inquiries about frontends
 or SANE should go to the SANE Developers mailing list