add tiflash store limit config version change note (#3635)

tiflash/tiflash-configuration.md

@@ -19,6 +19,11 @@ You can adjust the PD scheduling parameters using [pd-ctl](/pd-control.md). Note
     > The value of this parameter should be less than that of `region-schedule-limit`. Otherwise, the normal Region scheduling among TiKV nodes is affected.
 
 - [`store-balance-rate`](/pd-configuration-file.md#store-balance-rate): limits the rate at which Regions of each TiKV/TiFlash store are scheduled. Note that this parameter takes effect only when the stores have newly joined the cluster. If you want to change the setting for existing stores, use the following command.
+
+    > **Note:**
+    >
+    > Since v4.0.2, the `store-balance-rate` parameter has been deprecated and changes have been made to the `store limit` command. See [store-limit](/configure-store-limit.md) for details.
+
     - Execute the `pd-ctl -u <pd_ip:pd_port> store limit <store_id> <value>` command to set the scheduling rate of a specified store. (To get `store_id`, you can execute the `pd-ctl -u <pd_ip:pd_port> store` command. 
     - If you do not set the scheduling rate for Regions of a specified store, this store inherits the setting of `store-balance-rate`. 
     - You can execute the `pd-ctl -u <pd_ip:pd_port> store limit` command to view the current setting value of `store-balance-rate`.