Merge pull request #10 from Depado/documentation

Documentation in README.md

README.md

@@ -1,3 +1,34 @@
 # go-gin-prometheus
-===
+[![](https://godoc.org/github.com/zsais/go-gin-prometheus?status.svg)](https://godoc.org/github.com/zsais/go-gin-prometheus) [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
+
 Gin Web Framework Prometheus metrics exporter
+
+## Installation
+
+`$ go get github.com/zsais/go-gin-prometheus`
+
+## Usage
+
+```go
+package main
+
+import (
+	"github.com/gin-gonic/gin"
+	"github.com/zsais/go-gin-prometheus"
+)
+
+func main() {
+	r := gin.New()
+
+	p := ginprometheus.NewPrometheus("gin")
+	p.Use(r)
+
+	r.GET("/", func(c *gin.Context) {
+		c.JSON(200, "Hello world!")
+	})
+
+	r.Run(":29090")
+}
+```
+
+See the [example.go file](https://github.com/zsais/go-gin-prometheus/blob/master/example/example.go)