Prepare CLI for move into mainline

packages/cli/docs/src/plugin/interface/command.md

@@ -0,0 +1,21 @@
+# Command Functions
+
+> you can use command functions to execute some code & script
+
+Type Define:
+```
+Stdio: "Inherit" | "Piped" | "Null"
+```
+
+### `exec(commands: [string], stdout: Stdio, stderr: Stdio)`
+
+you can use this function to run some command on the current system.
+
+```lua
+local cmd = plugin.command
+
+manager.test = function ()
+    cmd.exec({"git", "clone", "https://github.com/DioxusLabs/cli-plugin-library"})
+end
+```
+> Warning: This function don't have exception catch.