docs: update slack count (#5842)

README.md

@@ -18,7 +18,7 @@
 <p align=center>
 <a href="https://pypi.org/project/jina/"><img alt="PyPI" src="https://img.shields.io/pypi/v/jina?label=Release&style=flat-square"></a>
 <a href="https://codecov.io/gh/jina-ai/jina"><img alt="Codecov branch" src="https://img.shields.io/codecov/c/github/jina-ai/jina/master?&logo=Codecov&logoColor=white&style=flat-square"></a>
-<a href="https://jina.ai/slack"><img src="https://img.shields.io/badge/Slack-3.6k-blueviolet?logo=slack&amp;logoColor=white&style=flat-square"></a>
+<a href="https://jina.ai/slack"><img src="https://img.shields.io/badge/Slack-4.8k-blueviolet?logo=slack&amp;logoColor=white&style=flat-square"></a>
 <a href="https://pypistats.org/packages/jina"><img alt="PyPI - Downloads from official pypistats" src="https://img.shields.io/pypi/dm/jina?style=flat-square"></a>
 <a href="https://github.com/jina-ai/jina/actions/workflows/cd.yml"><img alt="Github CD status" src="https://github.com/jina-ai/jina/actions/workflows/cd.yml/badge.svg"></a>
 </p>