add CodSpeed badge

Author: cometkim

README.md

@@ -3,6 +3,7 @@
 [![NPM Downloads](https://img.shields.io/npm/dw/unicode-segmenter)](https://npmjs.com/package/unicode-segmenter)
 [![Integration](https://github.com/cometkim/unicode-segmenter/actions/workflows/ci.yml/badge.svg)](https://github.com/cometkim/unicode-segmenter/actions/workflows/ci.yml)
 [![codecov](https://codecov.io/gh/cometkim/unicode-segmenter/graph/badge.svg?token=3rA29JEH4J)](https://codecov.io/gh/cometkim/unicode-segmenter)
+[![CodSpeed Badge](https://img.shields.io/endpoint?url=https://codspeed.io/badge.json)](https://codspeed.io/cometkim/unicode-segmenter)
 [![LICENSE - MIT](https://img.shields.io/github/license/cometkim/unicode-segmenter)](#license)
 
 A lightweight implementation of the [Unicode Text Segmentation (UAX \#29)](https://www.unicode.org/reports/tr29)