Add Gitpod configuration for quick setup of development environments

With this change, any developer can simply open a development environment in Gitpod. The environment has docs, web, and binary being built on every code change.

Also included the vscode extensions for Go and Docker.

Signed-off-by: Yarden Shoham <hrsi88@gmail.com>

README.md

@@ -11,6 +11,8 @@
 [![Matrix space](https://img.shields.io/matrix/ntfy-space:matrix.org?label=Matrix+space)](https://matrix.to/#/#ntfy-space:matrix.org)
 [![Reddit](https://img.shields.io/reddit/subreddit-subscribers/ntfy?color=%23317f6f&label=-%20r%2Fntfy&style=social)](https://www.reddit.com/r/ntfy/)
 [![Healthcheck](https://healthchecks.io/badge/68b65976-b3b0-4102-aec9-980921/kcoEgrLY.svg)](https://ntfy.statuspage.io/)
+[![Gitpod](https://img.shields.io/badge/Contribute%20with-Gitpod-908a85?logo=gitpod)](https://gitpod.io/#https://github.com/binwiederhier/ntfy)
+
 
 **ntfy** (pronounce: *notify*) is a simple HTTP-based [pub-sub](https://en.wikipedia.org/wiki/Publish%E2%80%93subscribe_pattern) notification service.
 It allows you to **send notifications to your phone or desktop via scripts** from any computer, entirely **without signup or cost**.
@@ -59,6 +61,12 @@ Or, if you'd like to help translate 🇩🇪 🇺🇸 🇧🇬, you can start im
 <img src="https://hosted.weblate.org/widgets/ntfy/-/multi-blue.svg" alt="Translation status" />
 </a>
 
+### Quickly getting a development environment setup
+
+To get a quick working development environment you could use Gitpod.
+
+[![Open in Gitpod](https://gitpod.io/button/open-in-gitpod.svg)](https://gitpod.io/#https://github.com/binwiederhier/ntfy)
+
 ## Sponsors
 I have just very recently started accepting donations via [GitHub Sponsors](https://github.com/sponsors/binwiederhier). 
 I would be humbled if you helped me carry the server and developer account costs. Even small donations are very much