Add smarter example with a combo

Author: MoOx

README.md

@@ -37,15 +37,15 @@ var output = postcss()
 console.log('\n====>Output CSS:\n', output)  
 ```
 
-Or just：
+Or just:
 
 ```js
 var output = postcss(selector())
   .process(css)
   .css
 ```
 
-input.css：
+input:
 
 ```css
 @custom-selector :--heading h1, h2, h3, h4, h5, h6;
@@ -97,6 +97,28 @@ a:visited {
 }
 ```
 
+You can even make some smart use like this:
+
+```css
+@custom-selector :--button button, .button;
+@custom-selector :--enter :hover, :focus;
+
+:--button:--enter {
+
+}
+```
+
+output
+
+```css
+button:hover,
+.button:hover,
+button:focus,
+.button:focus {
+
+}
+```
+
 ## Options
 
 ### `lineBreak`

test/index.js

@@ -219,6 +219,20 @@ h6:hover .ba--z {
     "should works with multilines definition"
   )
 
+  t.equal(
+    transform(
+      `@custom-selector :--button button, .button;
+@custom-selector :--enter :hover, :focus;
+
+:--button:--enter {}`
+    ).css,
+    `button:hover,
+.button:hover,
+button:focus,
+.button:focus {}`,
+    "should works with collapsed custom selectors"
+  )
+
   t.equal(
     transform(
       `@custom-selector :--any .foo, .bar;