Add information about how to serve a specific path (vercel#548)

* Add information about how to serve a specific path

* Fixed usage

* Fixed description

* Fixed name

Author: Johann-S

README.md

@@ -22,12 +22,18 @@ If you prefer, you can also install the package globally using [Yarn](https://ya
 yarn global add serve
 ```
 
-Once that's done, you can run this command inside your project's directory:
+Once that's done, you can run this command inside your project's directory...
 
 ```bash
 serve
 ```
 
+...or specify which folder you want to serve:
+
+```bash
+serve folder_name
+```
+
 Finally, run this command to see a list of all available options:
 
 ```bash

bin/serve.js

@@ -60,6 +60,7 @@ const getHelp = () => chalk`
 
       {bold $} {cyan serve} --help
       {bold $} {cyan serve} --version
+      {bold $} {cyan serve} folder_name
       {bold $} {cyan serve} [-l {underline listen_uri} [-l ...]] [{underline directory}]
 
       By default, {cyan serve} will listen on {bold 0.0.0.0:5000} and serve the
@@ -83,7 +84,7 @@ const getHelp = () => chalk`
       -c, --config                        Specify custom path to \`serve.json\`
 
       -n, --no-clipboard                  Do not copy the local address to the clipboard
-	  
+
       -u, --no-compression                Do not compress files
 
       --no-etag                           Send \`Last-Modified\` header instead of \`ETag\`