drivers: video: improve the format description docs

@verbatim shows the leading comment '*' fence in the output.
@code{.unparsed} allows extracting the text only.
In some formats, the pixels are also not immediately packed into fixed
number of bytes, like YUYV due to chroma subsampling. Disambiguate.
Add numbers marks on top to help identify the individual pixels.

Signed-off-by: Josuah Demangeon <me@josuah.net>

include/zephyr/drivers/video.h

@@ -810,7 +810,7 @@ void video_closest_frmival(const struct device *dev, enum video_endpoint_id ep,
 
 /**
  * @defgroup video_pixel_formats Video pixel formats
- * The @c | characters separate the pixels, and spaces separate the bytes.
+ * The '|' characters separate the pixels or logical blocks, and spaces separate the bytes.
  * The uppercase letter represents the most significant bit.
  * The lowercase letters represent the rest of the bits.
  * @{
@@ -856,38 +856,48 @@ void video_closest_frmival(const struct device *dev, enum video_endpoint_id ep,
  *
  * The full color information is spread over multiple pixels.
  *
+ * When the format includes more than 8-bit per pixel, a strategy becomes needed to pack
+ * the bits over multiple bytes, as illustrated for each format.
+ *
+ * The number above the 'R', 'r', 'G', 'g', 'B', 'b' are hints about which pixel number the
+ * following bits belong to.
+ *
  * @{
  */
 
 /**
- * @verbatim
- * | Bbbbbbbb | Gggggggg | Bbbbbbbb | Gggggggg | Bbbbbbbb | Gggggggg | ...
- * | Gggggggg | Rrrrrrrr | Gggggggg | Rrrrrrrr | Gggggggg | Rrrrrrrr | ...
- * @endverbatim
+ * @code{.unparsed}
+ *   0          1          2          3
+ * | Bbbbbbbb | Gggggggg | Bbbbbbbb | Gggggggg | ...
+ * | Gggggggg | Rrrrrrrr | Gggggggg | Rrrrrrrr | ...
+ * @endcode
  */
 #define VIDEO_PIX_FMT_BGGR8 VIDEO_FOURCC('B', 'A', '8', '1')
 
 /**
- * @verbatim
- * | Gggggggg | Bbbbbbbb | Gggggggg | Bbbbbbbb | Gggggggg | Bbbbbbbb | ...
- * | Rrrrrrrr | Gggggggg | Rrrrrrrr | Gggggggg | Rrrrrrrr | Gggggggg | ...
- * @endverbatim
+ * @code{.unparsed}
+ *   0          1          2          3
+ * | Gggggggg | Bbbbbbbb | Gggggggg | Bbbbbbbb | ...
+ * | Rrrrrrrr | Gggggggg | Rrrrrrrr | Gggggggg | ...
+ * @endcode
  */
 #define VIDEO_PIX_FMT_GBRG8 VIDEO_FOURCC('G', 'B', 'R', 'G')
 
 /**
- * @verbatim
- * | Gggggggg | Rrrrrrrr | Gggggggg | Rrrrrrrr | Gggggggg | Rrrrrrrr | ...
- * | Bbbbbbbb | Gggggggg | Bbbbbbbb | Gggggggg | Bbbbbbbb | Gggggggg | ...
- * @endverbatim
+ * @code{.unparsed}
+ *   0          1          2          3
+ * | Gggggggg | Rrrrrrrr | Gggggggg | Rrrrrrrr | ...
+ * | Bbbbbbbb | Gggggggg | Bbbbbbbb | Gggggggg | ...
+ * @endcode
  */
 #define VIDEO_PIX_FMT_GRBG8 VIDEO_FOURCC('G', 'R', 'B', 'G')
 
 /**
- * @verbatim
- * | Rrrrrrrr | Gggggggg | Rrrrrrrr | Gggggggg | Rrrrrrrr | Gggggggg | ...
- * | Gggggggg | Bbbbbbbb | Gggggggg | Bbbbbbbb | Gggggggg | Bbbbbbbb | ...
- * @endverbatim
+ * @code{.unparsed}
+ *   0          1          2          3
+ * | Rrrrrrrr | Gggggggg | Rrrrrrrr | Gggggggg | ...
+ * | Gggggggg | Bbbbbbbb | Gggggggg | Bbbbbbbb | ...
+ * @endcode
  */
 #define VIDEO_PIX_FMT_RGGB8 VIDEO_FOURCC('R', 'G', 'G', 'B')
 
@@ -905,10 +915,10 @@ void video_closest_frmival(const struct device *dev, enum video_endpoint_id ep,
  * 5 red bits [15:11], 6 green bits [10:5], 5 blue bits [4:0].
  * This 16-bit integer is then packed in big endian format over two bytes:
  *
- * @verbatim
+ * @code{.unparsed}
  *   15.....8 7......0
  * | RrrrrGgg gggBbbbb | ...
- * @endverbatim
+ * @endcode
  */
 #define VIDEO_PIX_FMT_RGB565X VIDEO_FOURCC('R', 'G', 'B', 'R')
 
@@ -916,19 +926,19 @@ void video_closest_frmival(const struct device *dev, enum video_endpoint_id ep,
  * 5 red bits [15:11], 6 green bits [10:5], 5 blue bits [4:0].
  * This 16-bit integer is then packed in little endian format over two bytes:
  *
- * @verbatim
+ * @code{.unparsed}
  *   7......0 15.....8
  * | gggBbbbb RrrrrGgg | ...
- * @endverbatim
+ * @endcode
  */
 #define VIDEO_PIX_FMT_RGB565 VIDEO_FOURCC('R', 'G', 'B', 'P')
 
 /**
  * The first byte is empty (X) for each pixel.
  *
- * @verbatim
+ * @code{.unparsed}
  * | Xxxxxxxx Rrrrrrrr Gggggggg Bbbbbbbb | ...
- * @endverbatim
+ * @endcode
  */
 #define VIDEO_PIX_FMT_XRGB32 VIDEO_FOURCC('B', 'X', '2', '4')
 
@@ -946,18 +956,18 @@ void video_closest_frmival(const struct device *dev, enum video_endpoint_id ep,
  * There is either a missing channel per pixel, U or V.
  * The value is to be averaged over 2 pixels to get the value of individual pixel.
  *
- * @verbatim
+ * @code{.unparsed}
  * | Yyyyyyyy Uuuuuuuu | Yyyyyyyy Vvvvvvvv | ...
- * @endverbatim
+ * @endcode
  */
 #define VIDEO_PIX_FMT_YUYV VIDEO_FOURCC('Y', 'U', 'Y', 'V')
 
 /**
  * The first byte is empty (X) for each pixel.
  *
- * @verbatim
+ * @code{.unparsed}
  * | Xxxxxxxx Yyyyyyyy Uuuuuuuu Vvvvvvvv | ...
- * @endverbatim
+ * @endcode
  */
 #define VIDEO_PIX_FMT_XYUV32 VIDEO_FOURCC('X', 'Y', 'U', 'V')