detect: function header return value clarification

Signed-off-by: Josh Soref <2119212+jsoref@users.noreply.github.com>

src/detect-target.c

@@ -76,8 +76,8 @@ void DetectTargetRegister(void) {
  *
  * \param targetstr Pointer to the user provided target options
  *
- * \retval targetd pointer to DetectTargetData on success
+ * \retval 0 on Success
- * \retval NULL on failure
+ * \retval -1 on Failure
  */
 static int DetectTargetParse(Signature *s, const char *targetstr)
 {