doc: modify doc about board setting

Author: fanghuaqi

doc/documents/example/example_usage_guide.doc

@@ -92,7 +92,7 @@
     ![Errors occur since the apply_embARC_patch.sh is not Unix format](pic/images/example/embARC101/embARC_apply_patches_with_error.jpg)
     - Run <em>bash <embARC>/apply_embARC_patch.sh</em> in shell environment (Linux or Cygwin) to download required source code and patch them.
     ![Download required source code and apply embARC patches](pic/images/example/embARC101/embARC_apply_patches.jpg)
-  - Seperate patch scripts location. You can also run the separate patch script to patch the source code that you need.
+  - Separate patch scripts location. You can also run the separate patch script to patch the source code that you need.
     - <em><embARC>/middleware/wolfssl/apply_embARC_patch.sh</em>
     - <em><embARC>/middleware/matrixssl/apply_embARC_patch.sh</em>
     - <em><embARC>/middleware/mbedtls/apply_embARC_patch.sh</em>
@@ -102,11 +102,12 @@
 
 \subsection subsect_example_usage_PFE_SetupBoardEnv Set Up the Board Environment
   + Set a WiFi hotspot with **WPA/WPA2 PSK** encrypted. Some changes in board/board.h should be made before running embARC examples.
+    - Take a look at the board/board.h, and go to corresponding header file, such as for emsk, you need to go to board/emsk/emsk.h
     - Set the WiFi hotspot name to "embARC" (just the characters in quotation marks).
     - Set the WiFi hotspot IP address range from "192.168.43.1" to "192.168.43.254".
     - Set the WiFi password to "qazwsxedc" (just the characters in quotation marks).
 
-      If the WiFi hotspot IP address settings cannot be changed, the settings in board/board.h must be modified.
+      If the WiFi hotspot IP address settings cannot be changed, the settings in the board setting header file must be modified.
       \code{.c}
       #define WF_IPADDR_1                   (192)
       #define WF_IPADDR_2                   (168)
@@ -160,7 +161,7 @@
     - The default UART baudrate is 115200 bps.
     - In the Tera Term menu, select **Setup** -> **Serial Port** and change the settings for port and baudrate.
 
-\note If the hotspot IP address range is not similar to "192.168.43.xxx", the IP address settings of the EMSK board should be changed in board/board.h. The baremetal examples don't support DHCP. A static IP address is required.
+\note If the hotspot IP address range is not similar to "192.168.43.xxx", the IP address settings of the EMSK board should be changed in corresponding board header file. The baremetal examples don't support DHCP. A static IP address is required.
 
 \section sect_example_usage_GeneralBuildSteps General Build and Run Steps
 \subsection subsect_example_usage_GBS_FastSteps Quick start