Update getting_started.md

Author: DonnaWuDongxia

doc/getting_started.md

@@ -29,8 +29,6 @@ make: Leaving directory '<your local dir>/src/person-tracking/build'
 gyp info ok
 ```
 
-Note: if error encounterred during the build process saied missing `boostXXX` file, please install the libboost using `sudo apt-get install libboost-all-dev`
-
 # Use C++ Add-on in Node.js Program
 After building it, it's time to test it in your `Node.js` program.  Unlike the standard `npm install <module-name>` way of using a module/add-on, you need to explicitly specify the directory in your `Node.js` program, e.g.
 
@@ -94,4 +92,8 @@ Pleaes refer to [Contribution Guide](./contribution.md) for more information.
     ```
     sudo modprobe uvcvideo
     ```
-
+- Error message says missing `boostXXX` file during building process
+    Need to install used libboost library as the following line.
+    ```
+    sudo apt-get install libboost-thread-dev
+    ```