text_style: (docs) fix hex channel order

Function actually works on #RRGGBB[AA] not #[AA]RRGGBB.

AARRGGBB is the order of color channel bytes (MSB...LSB) in the returned
integer.

include/vlc_text_style.h

@@ -246,7 +246,7 @@ VLC_API text_segment_t *text_segment_FromRuby( text_segment_ruby_t *p_ruby );
  *
  * @param psz_value An HTML color, which can be either:
  *  - A standard HTML color (red, cyan, ...) as defined in p_html_colors
- *  - An hexadecimal color, of the form [#][AA]RRGGBB
+ *  - An hexadecimal color, of the form [#]RRGGBB[AA]
  *  - A decimal-based color, of the form rgb(RRR,GGG,BBB) or rgba(RRR,GGG,BBB,AAA)
  * @param ok If non-null, true will be stored in this pointer to signal
  *           a successful conversion