doc: Update README.md

README.md

@@ -5,6 +5,7 @@ rehype-rewrite
 [![NPM version](https://img.shields.io/npm/v/rehype-rewrite.svg?style=flat)](https://npmjs.org/package/rehype-rewrite)
 [![Build](https://github.com/jaywcjlove/rehype-rewrite/actions/workflows/ci.yml/badge.svg)](https://github.com/jaywcjlove/rehype-rewrite/actions/workflows/ci.yml)
 [![Coverage Status](https://jaywcjlove.github.io/rehype-rewrite/badges.svg)](https://jaywcjlove.github.io/rehype-rewrite/lcov-report/)
+[![npm bundle size](https://img.shields.io/bundlephobia/minzip/rehype-rewrite)](https://bundlephobia.com/result?p=rehype-rewrite)
 
 Rewrite element with [rehype](https://github.com/rehypejs/rehype).