Telegram and Webhook sinks

What's Changed

• Documentation contribution docs on sphinx by @avinashupadhya99 in #182
• Instructions for installing robusta in different namespace by @avinashupadhya99 in #180
• Update README.md by @Shubh28698 in #179
• don't track replicas in the babysitter because it's extremely spammy with autoscaling by @aantn in #185
• Add severity to node health watcher by @aantn in #186
• Added python debug stack trace by @Avi-Robusta in #176
• add telegram sink by @arikalon1 in #190
• webhook sink by @arikalon1 in #192

New Contributors

• @avinashupadhya99 made their first contribution in #182

Full Changelog: 0.8.20...0.8.21