Update README.md (#2479)

Signed-off-by: Yusuke Kato <kpango@vdaas.org>

README.md

@@ -6,6 +6,7 @@
 
 [![License: Apache 2.0](https://img.shields.io/github/license/vdaas/vald.svg?style=flat-square)](https://opensource.org/licenses/Apache-2.0)
 [![release](https://img.shields.io/github/release/vdaas/vald.svg?style=flat-square)](https://github.com/vdaas/vald/releases/latest)
+[![CNCF Landscape](https://img.shields.io/badge/CNCF%20Landscape-5699C6)](https://landscape.cncf.io/?item=app-definition-and-development--database--vald)
 [![Go Reference](https://pkg.go.dev/badge/github.com/vdaas/vald.svg)](https://pkg.go.dev/github.com/vdaas/vald)
 [![Codacy Badge](https://img.shields.io/codacy/grade/a6e544eee7bc49e08a000bb10ba3deed?style=flat-square)](https://www.codacy.com/app/i.can.feel.gravity/vald?utm_source=github.com&utm_medium=referral&utm_content=vdaas/vald&utm_campaign=Badge_Grade)
 [![Go Report Card](https://goreportcard.com/badge/github.com/vdaas/vald?style=flat-square)](https://goreportcard.com/report/github.com/vdaas/vald)