fix manpages

chown.1

@@ -3,7 +3,7 @@
 chown \- change file ownership
 .SH SYNOPSIS
 .B chown
-.RB [ -Rr ]
+.RB [ \-Rr ]
 .RI [ owner ][: group ]
 .RI [ file ...]
 .SH DESCRIPTION
@@ -11,7 +11,7 @@ chown \- change file ownership
 changes the user or group ownership for the given files.
 .SH OPTIONS
 .TP
-.B -R, -r
+.B \-R, \-r
 change directory ownership recursively.
 .SH SEE ALSO
 .IR chown (2)