add a feature rank example

examples/feature-rank/main.go

@@ -0,0 +1,39 @@
+// This example shows how to use the feature ranking.
+package main
+
+import (
+	"fmt"
+
+	"github.com/go-gst/go-gst/examples"
+	"github.com/go-gst/go-gst/gst"
+)
+
+func start() (error) {
+	gst.Init(nil)
+
+	registry := gst.GetRegistry()
+
+	hardwareAccelerationRank := 258
+
+	codec, codecErr := registry.LookupFeature("vtdec_hw")
+
+	if codecErr == nil {
+		codec.SetPluginRank(hardwareAccelerationRank)
+		rank := codec.GetPluginRank()
+		fmt.Println("vtdec_hw rank is:", rank)
+	}
+
+	//add a feature you expect to be available to you here and change it's rank
+
+	return codecErr
+}
+
+func main() {
+	examples.Run(func() error {
+		var err error
+		if err = start(); err != nil {
+			return err
+		}
+		return nil
+	})
+}