add keywords utility example

example/stringx/replace/replace.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/tal-tech/go-zero/core/stringx"
+)
+
+func main() {
+	replacer := stringx.NewReplacer(map[string]string{
+		"PHP": "PPT",
+		"世界上": "吹牛",
+	})
+	fmt.Println(replacer.Replace("PHP是世界上最好的语言！"))
+}