--data-ascii: add mention

As it is a separate option it should have a .IP title

docs/curl.1

@@ -247,6 +247,8 @@ read the data from, or - if you want curl to read the data from stdin.  The
 contents of the file must already be URL-encoded. Multiple files can also be
 specified. Posting data from a file named 'foobar' would thus be done with
 \fI--data @foobar\fP.
+.IP "--data-ascii <data>"
+See \fI-d/--data\fP.
 .IP "--data-binary <data>"
 (HTTP) This posts data exactly as specified with no extra processing
 whatsoever.