media: docs: pixfmt: use section titles for bayer formats

The bayer formats have a subtitle, specifying how many bits
they use. Add a title markup to those, as otherwise they
look weird, specially at the PDF output.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

Documentation/userspace-api/media/v4l/pixfmt-srggb10-ipu3.rst

@@ -9,7 +9,9 @@
 V4L2_PIX_FMT_IPU3_SBGGR10 ('ip3b'), V4L2_PIX_FMT_IPU3_SGBRG10 ('ip3g'), V4L2_PIX_FMT_IPU3_SGRBG10 ('ip3G'), V4L2_PIX_FMT_IPU3_SRGGB10 ('ip3r')
 **********************************************************************************************************************************************
 
+====================
 10-bit Bayer formats
+====================
 
 Description
 ===========

Documentation/userspace-api/media/v4l/pixfmt-srggb14.rst

@@ -11,7 +11,9 @@ V4L2_PIX_FMT_SRGGB14 ('RG14'), V4L2_PIX_FMT_SGRBG14 ('GR14'), V4L2_PIX_FMT_SGBRG
 ***************************************************************************************************************************
 
 
+========================================
 14-bit Bayer formats expanded to 16 bits
+========================================
 
 
 Description

Documentation/userspace-api/media/v4l/pixfmt-srggb16.rst

@@ -11,7 +11,9 @@ V4L2_PIX_FMT_SRGGB16 ('RG16'), V4L2_PIX_FMT_SGRBG16 ('GR16'), V4L2_PIX_FMT_SGBRG
 ***************************************************************************************************************************
 
 
+====================
 16-bit Bayer formats
+====================
 
 
 Description

Documentation/userspace-api/media/v4l/pixfmt-srggb8.rst

@@ -10,8 +10,9 @@ V4L2_PIX_FMT_SRGGB8 ('RGGB'), V4L2_PIX_FMT_SGRBG8 ('GRBG'), V4L2_PIX_FMT_SGBRG8
 ***************************************************************************************************************************
 
 
+===================
 8-bit Bayer formats
-
+===================
 
 Description
 ===========