sort: add Slice example

Change-Id: I34ba4eaf1d232b639998ad3bbb0d075dd097722b
Reviewed-on: https://go-review.googlesource.com/33763
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dominik Honnef <dominik@honnef.co>

src/sort/example_test.go

@@ -22,3 +22,22 @@ func ExampleReverse() {
 	fmt.Println(s)
 	// Output: [6 5 4 3 2 1]
 }
+
+func ExampleSlice() {
+	people := []struct {
+		Name string
+		Age  int
+	}{
+		{"Gopher", 7},
+		{"Alice", 55},
+		{"Vera", 24},
+		{"Bob", 75},
+	}
+	sort.Slice(people, func(i, j int) bool { return people[i].Name < people[j].Name })
+	fmt.Println("By name:", people)
+
+	sort.Slice(people, func(i, j int) bool { return people[i].Age < people[j].Age })
+	fmt.Println("By age:", people)
+	// Output: By name: [{Alice 55} {Bob 75} {Gopher 7} {Vera 24}]
+	// By age: [{Gopher 7} {Vera 24} {Alice 55} {Bob 75}]
+}