media: Documentation: Added Digiteq Automotive MGB4 driver documentation

The "admin-guide" documentation for the Digiteq Automotive MGB4 driver.
Signed-off-by: Martin Tůma <martin.tuma@digiteqautomotive.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

Documentation/admin-guide/media/pci-cardlist.rst

@@ -77,6 +77,7 @@ ipu3-cio2         Intel ipu3-cio2 driver
 ivtv              Conexant cx23416/cx23415 MPEG encoder/decoder
 ivtvfb            Conexant cx23415 framebuffer
 mantis            MANTIS based cards
+mgb4              Digiteq Automotive MGB4 frame grabber
 mxb               Siemens-Nixdorf 'Multimedia eXtension Board'
 netup-unidvb      NetUP Universal DVB card
 ngene             Micronas nGene

Documentation/admin-guide/media/v4l-drivers.rst

@@ -17,6 +17,7 @@ Video4Linux (V4L) driver-specific documentation
 	imx7
 	ipu3
 	ivtv
+	mgb4
 	omap3isp
 	omap4_camera
 	philips