Revert "libvlc_media_get_tracks_info(): correct help"

This reverts commit 708a15ff.

include/vlc/libvlc_media.h

@@ -486,8 +486,20 @@ VLC_PUBLIC_API void *libvlc_media_get_user_data( libvlc_media_t *p_md );
 /**
  * Get media descriptor's elementary streams description
  *
- * Note, you need to call libvlc_media_parse() before calling this function.
- * Not doing this will result in an empty array.
+ * Note, you need to play the media _one_ time with --sout="#description"
+ * Not doing this will result in an empty array, and doing it more than once
+ * will duplicate the entries in the array each time. Something like this:
+ *
+ * @begincode
+ * libvlc_media_player_t *player = libvlc_media_player_new_from_media(media);
+ * libvlc_media_add_option_flag(media, "sout=#description");
+ * libvlc_media_player_play(player);
+ * // ... wait until playing
+ * libvlc_media_player_release(player);
+ * @endcode
+ *
+ * This is very likely to change in next release, and be done at the parsing
+ * phase.
  *
  * \param p_md media descriptor object
  * \param tracks address to store an allocated array of Elementary Streams