docs(intro): fix babel

docs/function.md

@@ -502,7 +502,7 @@ var arr2 = ['c'];
 var arr3 = ['d', 'e'];
 
 // ES5的合并数组
-arr1.concat(arr2, arr3));
+arr1.concat(arr2, arr3);
 // [ 'a', 'b', 'c', 'd', 'e' ]
 
 // ES6的合并数组

docs/intro.md

@@ -322,7 +322,7 @@ babel.transformFromAst(ast, code, options);
 ```javascript
 var es6Code = 'let x = n => n + 1';
 var es5Code = require('babel-core')
-  .transform(es5Code, {
+  .transform(es6Code, {
     presets: ['es2015']
   })
   .code;