doc: cmd: temperature: add documentation

Add documentation for the temperature command.

Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Reviewed-by: Simon Glass <sjg@chromium.org>

doc/usage/cmd/temperature.rst

@@ -0,0 +1,50 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+temperature command
+===================
+
+Synopsis
+--------
+
+::
+
+    temperature list
+    temperature get [thermal device name]
+
+Description
+-----------
+
+The *temperature* command is used to list thermal sensors and get their
+readings.
+
+The 'temperature list' command diplays the available thermal devices.
+
+The 'temperature get' command is used to get the reading in degrees C from
+the desired device which is selected by passing its device name.
+
+    thermal device name
+        device name of thermal sensor to select
+
+Example
+-------
+
+::
+
+
+    => temperature list
+    | Device                        | Driver                        | Parent
+    | tmon@610508110                | sparx5-temp                   | axi@600000000
+    =>
+    => temperature get tmon@610508110
+    tmon@610508110: 42 C
+
+Configuration
+-------------
+
+The *temperature* command is only available if CONFIG_CMD_TEMPERATURE=y.
+
+Return value
+------------
+
+The return value $? is set to 0 (true) if the command succeeded and to 1 (false)
+otherwise.

doc/usage/index.rst

@@ -68,6 +68,7 @@ Shell commands
    cmd/scp03
    cmd/setexpr
    cmd/size
+   cmd/temperature
    cmd/tftpput
    cmd/true
    cmd/ums