Merge pull request astaxie#857 from liuml07/patch-1

error() -> Error()

Author: astaxie

en/02.6.md

@@ -226,7 +226,7 @@ Looking back to the example of Box, you will find that Color implements interfac
 	fmt.Println("The biggest one is", boxes.BiggestsColor().String())
 	fmt.Println("The biggest one is", boxes.BiggestsColor())
 ```	
-Attention: If the type implemented the interface `error`, fmt will call `error()`, so you don't have to implement Stringer at this point.
+Attention: If the type implemented the interface `error`, fmt will call `Error()`, so you don't have to implement Stringer at this point.
 
 ### Type of variable in an interface