Fix a few spelling errors

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/fio.1 b/fio.1
index fa2ac70..77faa45 100644
--- a/fio.1
+++ b/fio.1
@@ -946,7 +946,7 @@
 .BI startdelay \fR=\fPirange
 Delay start of job for the specified number of seconds. Supports all time
 suffixes to allow specification of hours, minutes, seconds and
-milliseconds - seconds are the default if a unit is ommited.
+milliseconds - seconds are the default if a unit is omitted.
 Can be given as a range which causes each thread to choose randomly out of the
 range.
 .TP