docs: refine cli documentation (#2151)

Author: Sun Haoran

packages/docs/docs/api/cli.md

@@ -1,52 +1,80 @@
+---
+sidebarDepth: 3
+---
+
 # Command-line Interface
 
+Currently, there are four cli commands in VuePress: [build](#build), [dev](#dev), [eject](#eject) and [info](#info).
+
+If they are not enough for you, you can also create [your own commands](#more-commands).
+
 ## Usage
 
 ```bash
-vuepress <command> targetDir [options]
+vuepress <command> [options]
+
+Commands:
+  dev [targetDir]    start development server
+  build [targetDir]  build dir as static site
+  eject [targetDir]  copy the default theme into .vuepress/theme for customization.
+  info               Shows debugging information about the local environment
 ```
 
-## build
+You can always add `--help` flag for more information.
+
+## Commands
+
+### build
 
 Build dir as a static site.
 
-### -p, --port `<port>`
+#### -p, --port `<port>`
+
 See [port](../config/README.md#port).
 
-### -t, --temp `<temp>`
+#### -t, --temp `<temp>`
+
 See [temp](../config/README.md#temp).
 
-### -c, --cache `[cache]`
-### --no-cache
+#### -c, --cache `[cache]`
+
+#### --no-cache
+
 See [cache](../config/README.md#cache).
 
-### --dest `<dest>`
+#### -d, --dest `<dest>`
+
 See [dest](../config/README.md#dest).
 
-### --debug
+#### --debug
+
 Start development server in debug mode.
 
-### --silent
+#### --silent
+
 Start development server in silent mode.
 
-## dev
+### dev
 
 Start a development server. All options from `vuepress build` are available. And there are several options specifically for dev:
 
-### --host `<host>`
+#### --host `<host>`
+
 See [host](../config/README.md#host).
 
-### --open
+#### --open
+
 Open browser when ready.
 
-### --no-clear-screen
+#### --no-clear-screen
+
 Do not clear screen when dev server is ready. Note that dev server will not clear screen if you start it in debug mode.
 
-## eject
+### eject
 
 Copy the default theme into `.vuepress/theme` for customization.
 
-## info
+### info
 
 Shows debugging information about the local environment.
 

packages/vuepress/lib/checkEnv.js

@@ -7,7 +7,7 @@
 const { chalk, semver } = require('@vuepress/shared-utils')
 
 /**
- * Expose handleUnknownCommand function.
+ * Check if Node version meets VuePress requirement.
  */
 
 module.exports = function checkEnv (pkg) {