Fix description for options necessary by sane-hp-backend.

doc/scanadf.man

@@ -273,9 +273,9 @@ work at this time are:
 - Bell+Howell Copiscan II series scanners.
 .br
 .B sane-hp
-- Hewlett Packard scanners.  A patch to the sane-hp backend 
-is necessary.  The --scantype=ADF option must be specified (earlier
-versions of the backend used the --scan-from-adf option, instead).
+- Hewlett Packard scanners.  The --source=ADF option must be specified (earlier
+versions of the backend used the options --scantype=ADF
+or --scan-from-adf option, instead).
 .br
 .B sane-umax
 - UMAX scanners.  Support exists in build 12 and later.