imx: Add documentation for imx specific commands

CONFIG_CMD_HDMIDETECT
CONFIG_CMD_BMODE
Signed-off-by: NRobert Winkler <robert.winkler@boundarydevices.com>
Acked-by: NOtavio Salvador <otavio@ossystems.com.br>

README

@@ -2598,6 +2598,21 @@ CBFS (Coreboot Filesystem) support
 		Note: There is also a sha1sum command, which should perhaps
 		be deprecated in favour of 'hash sha1'.
 
+- Freescale i.MX specific commands:
+		CONFIG_CMD_HDMIDETECT
+		This enables 'hdmidet' command which returns true if an
+		HDMI monitor is detected.  This command is i.MX 6 specific.
+
+		CONFIG_CMD_BMODE
+		This enables the 'bmode' (bootmode) command for forcing
+		a boot from specific media.
+
+		This is useful for forcing the ROM's usb downloader to
+		activate upon a watchdog reset which is nice when iterating
+		on U-Boot.  Using the reset button or running bmode normal
+		will set it back to normal.  This command currently
+		supports i.MX53 and i.MX6.
+
 - Signing support:
 		CONFIG_RSA