w1: w1_therm: Document Maxim MAX31850 thermoelement IF.

w1_therm driver supports now MAX31850, too. Add it to documentation
and fix a small typo.

Signed-off-by: Markus Reichl <m.reichl@fivetechno.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/w1/slaves/w1_therm.rst

@@ -6,7 +6,8 @@ Supported chips:
 
   * Maxim ds18*20 based temperature sensors.
   * Maxim ds1825 based temperature sensors.
-  * GXCAS GC20MH01 temperature sensor.
+  * GXCAS GX20MH01 temperature sensor.
+  * Maxim MAX31850 thermoelement interface.
 
 Author: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
 
@@ -15,7 +16,7 @@ Description
 -----------
 
 w1_therm provides basic temperature conversion for ds18*20, ds28ea00, GX20MH01
-devices.
+and MAX31850 devices.
 
 Supported family codes:
 
@@ -137,3 +138,7 @@ bits in Config register; R2 bit in Config register enabling 13 and 14 bit
 resolutions. The device is powered up in 14-bit resolution mode. The conversion
 times specified in the datasheet are too low and have to be increased. The
 device supports driver features ``1`` and ``2``.
+
+MAX31850 device shares family number 0x3B with DS1825. The device is generally
+compatible with DS1825. The higher 4 bits of Config register read all 1,
+indicating 15, but the device is always operating in 14-bit resolution mode.