[NPU doc] Add ARL runtime configuration (#12562)

docs/mddocs/Quickstart/npu_quickstart.md

@@ -88,20 +88,21 @@ For `ipex-llm` NPU support, please set the following environment variable with a
 - For **Intel Core™ Ultra Processors (Series 2) with processor number 2xxV (code name Lunar Lake)**:
 
   - For Intel Core™ Ultra 7 Processor 258V:
-      ```cmd
-      set BIGDL_USE_NPU=1
-      ```
+      No runtime configuration required.
 
   - For Intel Core™ Ultra 5 Processor 228V & 226V:
       ```cmd
-      set BIGDL_USE_NPU=1
       set IPEX_LLM_NPU_DISABLE_COMPILE_OPT=1
       ```
 
+- For **Intel Core™ Ultra Processors (Series 2) with processor number 2xxK (code name Arrow Lake)**:
+   ```cmd
+   set IPEX_LLM_NPU_DISABLE_COMPILE_OPT=1
+   ```
+
 - For **Intel Core™ Ultra Processors (Series 1) with processor number 1xxH (code name Meteor Lake)**:
 
-   ```bash
-   set BIGDL_USE_NPU=1
+   ```cmd
    set IPEX_LLM_NPU_MTL=1
    ```