update doc. #412

site/src/site/sphinx/en/quick-start.md

@@ -96,8 +96,10 @@ java.home              /Library/Java/JavaVir
 
 ## 4. Get the Main Class of the `arthas-demo` process with the thread command
 
+`thread 1` will print the stack of the thread with ID 1, which usually the main function thread.
+
 ```bash
-$ thread -n -1 | grep 'main('
+$ thread 1 | grep 'main('
     at demo.MathGame.main(MathGame.java:17)
 ```
 

site/src/site/sphinx/quick-start.md

@@ -97,8 +97,10 @@ java.home              /Library/Java/JavaVir
 
 ## 4. 通过thread命令来获取到`arthas-demo`进程的Main Class
 
+`thread 1`会打印线程ID 1的栈，通常是main函数的线程。
+
 ```bash
-$ thread -n -1 | grep 'main('
+$ thread 1 | grep 'main('
     at demo.MathGame.main(MathGame.java:17)
 ```