fio.1: fix hyphen-used-as-minus-sign

Signed-off-by: Michael Prokop <mika@grml.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fio.1 b/fio.1
index b3925b5..9b1e02b 100644
--- a/fio.1
+++ b/fio.1
@@ -45,7 +45,7 @@
 .TP
 .BI \-\-debug \fR=\fPtype
 Enable verbose tracing of various fio actions. May be `all' for all types
-or individual types seperated by a comma (eg --debug=io,file). `help' will
+or individual types seperated by a comma (eg \-\-debug=io,file). `help' will
 list all available tracing options.
 .TP
 .B \-\-help