Use a 'V' symbol for voltage unit

Currently webui-vue displays all sensor data with units written as
symbols ('A', 'W', 'C', 'RPM') except for voltage which is written as
'Volts'.
Use a 'V' symbol for voltage unit for unification.

Change-Id: I257b6d6bf1d099f62a861430a6448368b56dace1
Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>

src/store/modules/HardwareStatus/SensorsStore.js

@@ -110,7 +110,7 @@ const SensorsStore = {
               upperCaution: sensor.UpperThresholdNonCritical,
               lowerCritical: sensor.LowerThresholdCritical,
               upperCritical: sensor.UpperThresholdCritical,
-              units: 'Volts',
+              units: 'V',
             };
           });
           commit('setSensors', sensorData);