add id.420129.xyz

close #635

Author: unixfox

docs/instances.md

@@ -12,6 +12,7 @@
 
 * [inv.nadeko.net](https://inv.nadeko.net) 🇨🇱 - Source code/changes: https://git.nadeko.net/Fijxu/invidious - CAPTCHA: mCaptcha (https://mcaptcha.org/)
 * [yewtu.be](https://yewtu.be) 🇩🇪 - Source code/changes: https://github.com/yewtudotbe/invidious-custom
+* [id.420129.xyz](https://id.420129.xyz) 🇩🇪  
 
 ### Tor Onion Services: