rt2800usb: make Kconfig help entry more helpful

Document known issues with the driver to aid distribution makers,
users and developers in making informed decisions instead of wasting
their time needlessly.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/Kconfig

@@ -104,7 +104,7 @@ config RT73USB
 	  When compiled as a module, this driver will be called rt73usb.
 
 config RT2800USB
-	tristate "Ralink rt2800 (USB) support"
+	tristate "Ralink rt2800 (USB) support (EXPERIMENTAL)"
 	depends on USB && EXPERIMENTAL
 	select RT2X00_LIB_USB
 	select RT2X00_LIB_HT
@@ -115,6 +115,10 @@ config RT2800USB
 	  This adds experimental support for rt2800 wireless chipset family.
 	  Supported chips: RT2770, RT2870 & RT3070.
 
+	  Known issues:
+	  - support for RT2870 chips doesn't work with 802.11n APs yet
+	  - support for RT3070 chips is non-functional at the moment
+
 	  When compiled as a module, this driver will be called "rt2800usb.ko".
 
 config RT2X00_LIB_PCI