docs: Add onChangeThreshold in Device AutoEvent

The onChange flag in Device AutoEvent can prevent any non changed values sent out. The onChangeThreshold could provide the advanced feature, and the default value is 0, any changed value that exceeds (>) bounds shall be published.

Signed-off-by: bruce <[email protected]>

openapi/core-metadata.yaml

@@ -57,6 +57,9 @@ components:
         onChange:
           type: boolean
           description: OnChange indicates whether the device service will generate an event only, if the reading value is different from the previous one. If true, only generate events when readings change
+        onChangeThreshold:
+          type: number
+          description: OnChangeThreshold indicates any changed value that exceeds the threshold shall be generated new event if `onChange` is true, this feature only applies to the numeric reading. Available value types are `Uint8`, `Uint16`, `Uint32`, `Uint64`, `Int8`, `Int16`, `Int32`, `Int64`, `Float32`, `Float64`. The default value is 0.
         sourceName:
           type: string
           description: SourceName indicates the name of the resource or device command in the device profile which describes the event to generate
@@ -1315,6 +1318,7 @@ components:
             autoEvents:
               - interval: 300ms
                 onChange: true
+                onChangeThreshold: 0.01
                 sourceName: CurrentHumidity
             protocols:
               modbus-tcp:
@@ -1348,6 +1352,7 @@ components:
             autoEvents:
               - interval: "100ms"
                 onChange: true
+                onChangeThreshold: 0.01
                 sourceName: "CurrentHumidity"
         - apiVersion: v3
           device: