Document default login credentials and wp-env run command (#20678)

* Document default login credentials and run command

* Add more descriptive CLI help messages

* Update README.md

* Update wording in `run` command description

* Fix typo in cli.js

* Fix linting errors

* Remove extra ;

* Whitespace

packages/env/README.md

@@ -43,7 +43,7 @@ Then, start the local environment:
 $ wp-env start
 ```
 
-Finally, navigate to http://localhost:8888 in your web browser to see WordPress running with the local WordPress plugin or theme running and activated.
+Finally, navigate to http://localhost:8888 in your web browser to see WordPress running with the local WordPress plugin or theme running and activated. Default login credentials are username: `admin` password: `password`.
 
 ### Stopping the environment
 
@@ -175,6 +175,32 @@ Positionals:
             [string] [choices: "all", "development", "tests"] [default: "tests"]
 ```
 
+### `wp-env run [container] [command]` 
+
+```sh
+wp-env run <container> [command..]
+
+Runs an arbitrary command in one of the underlying Docker containers, for
+example it's useful for running wp cli commands.
+
+
+Positionals:
+  container  The container to run the command on.            [string] [required]
+  command    The command to run.                           [array] [default: []]
+```
+
+For example:
+
+```sh
+wp-env run cli wp user list
+⠏ Running `wp user list` in 'cli'.
+
+ID      user_login      display_name    user_email      user_registered roles
+1       admin   admin   [email protected]   2020-03-05 10:45:14     administrator
+
+✔ Ran `wp user list` in 'cli'. (in 2s 374ms)
+```
+
 ## .wp-env.json
 
 You can customize the WordPress installation, plugins and themes that the development environment will use by specifying a `.wp-env.json` file in the directory that you run `wp-env` from.

packages/env/lib/cli.js

@@ -111,7 +111,7 @@ module.exports = function cli() {
 	);
 	yargs.command(
 		'run <container> [command..]',
-		'Runs an arbitrary command in one of the underlying Docker containers.',
+		"Runs an arbitrary command in one of the underlying Docker containers, for example it's useful for running wp cli commands.",
 		( args ) => {
 			args.positional( 'container', {
 				type: 'string',
@@ -124,6 +124,10 @@ module.exports = function cli() {
 		},
 		withSpinner( env.run )
 	);
+	yargs.example(
+		'$0 run cli wp user list',
+		'Runs `wp user list` wp-cli command which lists WordPress users.'
+	);
 
 	return yargs;
 };