Zulip badge

[VeckoTheGecko]

Add badge to Community Zulip in README

Will add badge with link once available to the public

(Aside, in #2310 will need to be added to a community section)

[VeckoTheGecko]

We can use https://img.shields.io/badge/Zulip-50ADFF?style=for-the-badge&logo=Zulip&logoColor=white

[reint-fischer]

I have added it to the new community page in #2349

[VeckoTheGecko]

Thanks, closing as completed