Update readme.

README.md

@@ -4,4 +4,51 @@
 [![Go Report Card](https://goreportcard.com/badge/github.com/onrik/magic)](https://goreportcard.com/report/github.com/onrik/magic)
 [![GoDoc](https://godoc.org/github.com/onrik/magic?status.svg)](https://godoc.org/github.com/onrik/magic)
 
-Magic converter
+## Magic converter for differect structs
+By default:
+1. Map same types with same names
+1. Map slices with same types 
+1. Map types to pointers and backwards (for example: int to *int) 
+1. Returns error on types mismatch
+
+By options:
+1. Custom converters for different types
+1. Custom mapping for different fields names
+
+Examples:
+```go
+package main
+
+import (
+	"fmt"
+
+	"github.com/onrik/magic"
+)
+
+type User1 struct {
+	ID       int
+	Name     string
+	Password string
+	Age      int
+}
+
+type User2 struct {
+	ID   int
+	Name string
+	Age  *int
+}
+
+func main() {
+	user1 := User1{
+		ID:       1,
+		Name:     "John",
+		Password: "111",
+		Age:      21,
+	}
+	user2 := User2{}
+
+	err := magic.Map(user1, &user2)
+	fmt.Println(err)
+	fmt.Printf("%+v\n", user2)
+}
+```