[media] doc-rst: convert fourcc to rst format

Fix fourcc for it to be correcly parsed by Sphinx.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/media/v4l-drivers/fourcc.rst

@@ -8,24 +8,22 @@ other three characters depends on the first one.
 
 Existing 4CCs may not obey these guidelines.
 
-Formats
-=======
-
 Raw bayer
 ---------
 
 The following first characters are used by raw bayer formats:
 
-	B: raw bayer, uncompressed
-	b: raw bayer, DPCM compressed
-	a: A-law compressed
-	u: u-law compressed
+- B: raw bayer, uncompressed
+- b: raw bayer, DPCM compressed
+- a: A-law compressed
+- u: u-law compressed
 
 2nd character: pixel order
-	B: BGGR
-	G: GBRG
-	g: GRBG
-	R: RGGB
+
+- B: BGGR
+- G: GBRG
+- g: GRBG
+- R: RGGB
 
 3rd character: uncompressed bits-per-pixel 0--9, A--
 

Documentation/media/v4l-drivers/index.rst

@@ -18,4 +18,5 @@ License".
 .. toctree::
 	:maxdepth: 5
 
+	fourcc
 	cardlist