docs: add Codecov badge to README files (#2837)

Author: caio-pizzol

README.md

@@ -11,6 +11,7 @@
 <div align="center">
   <a href="https://www.npmjs.com/package/superdoc" target="_blank"><img src="https://img.shields.io/npm/v/superdoc.svg?color=1355ff" height="22px"></a>
   <a href="https://www.npmjs.com/package/superdoc" target="_blank"><img src="https://img.shields.io/npm/dm/superdoc.svg?color=1355ff" height="22px"></a>
+  <a href="https://codecov.io/gh/superdoc-dev/superdoc" target="_blank"><img src="https://codecov.io/gh/superdoc-dev/superdoc/branch/main/graph/badge.svg" height="22px"></a>
   <a href="https://www.gnu.org/licenses/agpl-3.0" target="_blank"><img src="https://img.shields.io/badge/License-AGPL%20v3-1355ff.svg?color=1355ff" height="22px"></a>
   <a href="https://github.com/superdoc-dev/superdoc" target="_blank"><img src="https://img.shields.io/github/stars/superdoc-dev/superdoc?style=flat&color=1355ff" height="22px"></a>
   <a href="https://discord.com/invite/b9UuaZRyaB" target="_blank"><img src="https://img.shields.io/badge/discord-join-1355ff" height="22px"></a>

packages/superdoc/README.md

@@ -5,6 +5,7 @@
 [![Documentation](https://img.shields.io/badge/docs-available-1355ff.svg)](https://docs.superdoc.dev/)
 [![License: AGPL v3](https://img.shields.io/badge/License-AGPL%20v3-1355ff.svg)](https://www.gnu.org/licenses/agpl-3.0)
 [![npm version](https://img.shields.io/npm/v/superdoc.svg?color=1355ff)](https://www.npmjs.com/package/superdoc)
+[![codecov](https://codecov.io/gh/superdoc-dev/superdoc/branch/main/graph/badge.svg)](https://codecov.io/gh/superdoc-dev/superdoc)
 [![Discord](https://img.shields.io/badge/discord-join-1355ff)](https://discord.com/invite/b9UuaZRyaB)
 
 SuperDoc renders and edits DOCX files in the browser. Built on OOXML — not bolted onto HTML. As you type, you write directly to the XML. Import a document, edit it, export it. Nothing lost.