hwmon: (amd_energy) Update driver documentation

Update the documentation with the newly added features
* Set the accumulation interval based on resolution
Signed-off-by: Naveen Krishna Chatradhi <nchatrad@amd.com>
Link: https://lore.kernel.org/r/20200929105322.8919-5-nchatrad@amd.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/amd_energy.rst

@@ -84,6 +84,11 @@ per run to a respective 64-bit counter. The kernel thread starts
 running during probe, wakes up every 100secs and stops running
 when driver is removed.
 
+Frequency of the accumulator thread is set during the probe
+based on the chosen energy unit resolution. For example
+A. fine grain (1.625 micro J)
+B. course grain (0.125 milli J)
+
 A socket and core energy read would return the current register
 value added to the respective energy accumulator.