update/fix invidious demo link

fixes https://github.com/awesome-selfhosted/awesome-selfhosted/issues/2961

README.md

@@ -1179,7 +1179,7 @@ _See also: [List of streaming media systems - Wikipedia](https://en.wikipedia.or
 - [Bluecherry](https://www.bluecherrydvr.com/) - Closed-circuit television (CCTV) software application which supports IP and Analog cameras. ([Source Code](https://github.com/bluecherrydvr/bluecherry-apps)) `GPL-2.0` `PHP`
 - [CyTube](https://github.com/calzoneman/sync) - CyTube is a web application providing media synchronization, chat, and more for an arbitrary number of channels. ([Demo](https://cytu.be)) `MIT` `Nodejs`
 - [Hellowlol HTPC Manager fork](https://github.com/Hellowlol/HTPC-Manager) - Fully responsive interface to manage all your favorite media on your HTPC. `MIT` `Python`
-- [Invidious](https://github.com/iv-org/invidious) - `⚠` Invidious is an alternative front-end to YouTube. ([Demo](https://docs.invidious.io/Invidious-Instances.md)) `AGPL-3.0` `Crystal`
+- [Invidious](https://github.com/iv-org/invidious) - `⚠` Invidious is an alternative front-end to YouTube. ([Demo](https://docs.invidious.io/instances/)) `AGPL-3.0` `Crystal`
 - [Kerberos.io](https://kerberos.io) - Kerberos.io is a video surveillance solution, which works with any camera and on every Linux based machine (Raspberry Pi, Docker, Kubernetes cluster). ([Demo](https://demo.kerberos.io/), [Source Code](https://github.com/kerberos-io/kerberos-docker)) `MIT` `C++`
 - [MediaCMS](https://mediacms.io) - MediaCMS is a modern, fully featured open source video and media CMS, written in Python/Django/React, featuring a REST API. ([Source Code](https://github.com/mediacms-io/mediacms)) `AGPL-3.0` `Python/Docker`
 - [Myflix](https://github.com/farfalleflickan/Myflix) `⚠` - Self-hosted, super lightweight Netflix alternative. `MIT` `Shell`