Adds some documentation and README

examples/example.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"time"
+
+	"github.com/gin-contrib/cors"
+	"github.com/gin-gonic/gin"
+)
+
+func main() {
+	router := gin.Default()
+	// CORS for https://foo.com and https://github.com origins, allowing:
+	// - PUT and PATCH methods
+	// - Origin header
+	// - Credentials share
+	// - Preflight requests cached for 12 hours
+	router.Use(cors.New(cors.Config{
+		AllowOrigins:     []string{"https://foo.com"},
+		AllowMethods:     []string{"PUT", "PATCH"},
+		AllowHeaders:     []string{"Origin"},
+		ExposeHeaders:    []string{"Content-Length"},
+		AllowCredentials: true,
+		AllowOriginFunc: func(origin string) bool {
+			return origin == "https://github.com"
+		},
+		MaxAge: 12 * time.Hour,
+	}))
+	router.Run()
+}