man: Add missing options markup

The options should be always in bold.

man/update-alternatives.1

@@ -319,12 +319,12 @@ might contain spaces).
 .TP
 \fB\-\-set\-selections\fR
 Read configuration of alternatives on standard input in the format
-generated by \-\-get\-selections\fR and reconfigure
+generated by \fB\-\-get\-selections\fR and reconfigure
 them accordingly (since version 1.15.0).
 .TP
 \fB\-\-query\fR \fIname\fR
 Display information about the link group
-like \-\-display does, but in a machine parseable way
+like \fB\-\-display\fP does, but in a machine parseable way
 (since version 1.15.0, see section \fBQUERY FORMAT\fR below).
 .TP
 \fB\-\-list\fR \fIname\fR