doc: install doc add command usage

INSTALL.md

@@ -53,6 +53,15 @@ $ docker start answer
      connection: [username]:[password]@tcp([host]:[port])/[DbName]
   7. Exit the data directory and execute ./answer run -c ./data/conf/config.yaml
 
+## Available Commands
+Usage: answer [command]
+
+- help: Help about any command
+- init: Init answer application
+- run: Run answer application
+- check: Check answer required environment
+- dump: Backup answer data
+
 ## config.yaml Description
 
 ```

INSTALL_CN.md

@@ -52,6 +52,15 @@ $ docker start answer
      connection: [username]:[password]@tcp([host]:[port])/[DbName]
  7. 退出data 目录 执行 ./answer run -c ./data/conf/config.yaml
 
+## 当前支持的命令
+用法: answer [command]
+
+- help: 帮助
+- init: 初始化环境
+- run: 启动
+- check: 环境依赖检查
+- dump: 备份数据
+
 ## 配置文件 config.yaml 参数说明
 
 ```