libtraceevent: Fix typo in tep_plugin_add_option() description

A typo "optiona" -> "optional" is fixed in description of
tep_plugin_add_option() API.

Link: https://lore.kernel.org/r/CAM9d7cizjF+fbK7YzmsBDgrx__4YAOsmEq67D3sWET8FF+YdFA@mail.gmail.com
Link: https://lore.kernel.org/linux-trace-devel/[email protected]
Link: https://lore.kernel.org/linux-trace-devel/[email protected]

Suggested-by: Namhyung Kim <[email protected]>
Signed-off-by: Tzvetomir Stoyanov (VMware) <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: [email protected]
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Steven Rostedt (VMware) <[email protected]>
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: tzstoyanov

tools/lib/traceevent/event-plugin.c

@@ -310,7 +310,7 @@ static int process_option(const char *plugin, const char *option, const char *va
 /**
  * tep_plugin_add_option - add an option/val pair to set plugin options
  * @name: The name of the option (format: <plugin>:<option> or just <option>)
- * @val: (optiona) the value for the option
+ * @val: (optional) the value for the option
  *
  * Modify a plugin option. If @val is given than the value of the option
  * is set (note, some options just take a boolean, so @val must be either