[feat] add readme

README.md

@@ -0,0 +1,58 @@
+# Config Loader
+
+## Install
+```
+go get -u git.trj.tw/golang/config-loader
+```
+
+## Usage
+
+### struct tag
+> default : default value define
+> length : use for slice type min default length
+
+### support type
+- string
+- int, int8, int16, int32, int64
+- uint, uint8, uint16, uint32, uint64
+- float32, float64
+- bool
+- struct
+- slice
+  - []string
+  - []int, []int8, []int16, []int32, []int64
+  - []uint, []uint8, []uint16, []uint32, []uint64
+  - []float32, []float64
+  - []bool
+  - []struct
+
+### example
+```go
+package main
+
+import (
+  "fmt"
+  "log"
+
+  confloader "git.trj.tw/golang/config-loader"
+)
+
+type Server struct {
+  Port int `json:"port" default:"10230"`
+}
+type Config struct {
+  Server     Server
+  Switchs    []int  `json:"switchs" default:"1" length:"2"`
+  URL        string `json:"url" default:"https://google.com"`
+  OutputFile bool   `json:"output_file" default:"true"`
+}
+
+func main() {
+  conf := &Config{}
+  if err := confloader.Load(conf, nil); err != nil {
+    log.Fatal(err)
+  }
+
+  fmt.Println(conf)
+}
+```