docs: add custom router group

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

Author: appleboy

README.md

@@ -54,6 +54,34 @@ func main() {
 }
 ```
 
+### custom router group
+
+```go
+package main
+
+import (
+	"net/http"
+
+	"github.com/gin-contrib/pprof"
+	"github.com/gin-gonic/gin"
+)
+
+func main() {
+	router := gin.Default()
+	pprof.Register(router)
+	adminGroup := r.Group("/admin", func(c *gin.Context) {
+		if c.Request.Header.Get("Authorization") != "foobar" {
+			c.AbortWithStatus(http.StatusForbidden)
+			return
+		}
+		c.Next()
+	})
+	pprof.RouteRegister(adminGroup, "pprof")
+	router.Run(":8080")
+}
+
+```
+
 ### Use the pprof tool
 
 Then use the pprof tool to look at the heap profile:

example/custom/server.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"net/http"
+
+	"github.com/gin-contrib/pprof"
+	"github.com/gin-gonic/gin"
+)
+
+func main() {
+	router := gin.Default()
+	pprof.Register(router)
+	adminGroup := r.Group("/admin", func(c *gin.Context) {
+		if c.Request.Header.Get("Authorization") != "foobar" {
+			c.AbortWithStatus(http.StatusForbidden)
+			return
+		}
+		c.Next()
+	})
+	pprof.RouteRegister(adminGroup, "pprof")
+	router.Run(":8080")
+}