docs(global): add contributing docs

Also note that we're only support Deno at the moment.

CONTRIBUTING.md

@@ -0,0 +1,14 @@
+# Contributing guidelines
+
+Thanks for your interest in extending the CLI's feature set! Although it is
+small at the moment (and relatively feature complete for now), we are open for
+patches related to bug fixes and porting to other runtimes.
+
+## Preflight checklist
+
+* Agree to the [community code of conduct](https://policies.recaptime.dev/code-of-conduct)
+and [the Linux DCO](https://developercertificate.org/).
+
+## Prerequisites for CLI dev
+
+* [Deno](https://deno.com) (v2.x preferred)

README.md

@@ -6,6 +6,9 @@ instead of [`npm:commander`](https://npmjs.com/package/commander).
 
 ## Install
 
+> **Note**: Currently works only on Deno for now, but feel free to contribute patches
+> for npm and bun support
+
 Requires Tailscale to be installed and authenicated with MagicDNS enabled
 if you want to use the default base URL.