README: remove broken link to old rocket.chat instance

the updated link is already available in CONTRIBUTING.md

README.md

@@ -1389,7 +1389,6 @@ See also [Documentation Generators](#documentation-generators), [Wikimatrix](htt
 
 **[`^        back to top        ^`](#)**
 
-- [Awesome Selfhosted Chat](https://chat.awesome-selfhosted.com) - Rocket.chat instance setup for the awesome selfhosted community.
 - [Awesome Big Data](https://github.com/onurakpolat/awesome-bigdata) - Curated list of awesome big data frameworks, resources and other awesomeness.
 - [Awesome Sysadmin](https://github.com/n1trux/awesome-sysadmin) - Curated list of amazingly awesome open source sysadmin resources.
 - [PRISM Break](https://prism-break.org/en/), [privacytools.io](https://www.privacytools.io/), [Alternative Internet](https://redecentralize.github.io/alternative-internet/), [Libre Projects](http://libreprojects.net/) - Lists of software aimed at privacy and decentralization (in some form).