doc: some small man page corrections.

doc/sane-canon_dr.man

@@ -161,7 +161,7 @@ Some scanners pad the upper edge of one side of a duplex scan. There is some var
 .RE
 .PP
 .BR NOTE :
-'option' lines may appear multiple times in the configuration file.
+"option" lines may appear multiple times in the configuration file.
 They only apply to scanners discovered by the next 'scsi/usb' line.
 .PP
 

doc/sane-pixma.man

@@ -184,7 +184,7 @@ an up-to-date status at the project homepage. (See below).
 Users feedback is essential to help improve features and performances.
 .SH OPTIONS
 Besides "well-known" options (e.g. resolution, mode etc.)
-.Bsane\-pixma
+.B sane\-pixma
 backend also
 provides the following options, i.e. the options might change in the future.
 .br

doc/sane-scsi.man

@@ -122,7 +122,7 @@ $ chmod 660 /dev/sg0
 .RE
 .PP
 When your system uses the device filesystem (devfs), you have to edit
-.BIR /etc/devfs/perms.
+.IR /etc/devfs/perms.
 There you should search the line
 .PP
 .RS
@@ -172,7 +172,7 @@ If there are no
 devices, just do a
 .I sh MAKEDEV uk0
 in the
-.i /dev
+.I /dev
 directory. The scanner should then be accessible as
 .I /dev/uk0
 if it was probed during boot.