V4L/DVB (5587): Add help for RADIO_ADAPTERS and VIDEO_CAPTURE_DRIVERS

Add a small help for those two new Kconfig vars.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
diff --git a/drivers/media/video/Kconfig b/drivers/media/video/Kconfig
index 29f7b71..5cb3f54 100644
--- a/drivers/media/video/Kconfig
+++ b/drivers/media/video/Kconfig
@@ -6,6 +6,10 @@
 	bool "Video capture adapters"
 	depends on VIDEO_DEV
 	default y
+	---help---
+	  Say Y here to enable selecting the video adapters for
+	  webcams, analog TV, and hybrid analog/digital TV.
+	  Some of those devices also supports FM radio.
 
 if VIDEO_CAPTURE_DRIVERS