docs: Add prototype warning in readme, add insiders goal date

Author: pawamoy

README.md

@@ -4,7 +4,10 @@
 [![gitpod](https://img.shields.io/badge/gitpod-workspace-708FCC.svg?style=flat)](https://gitpod.io/#https://github.com/mkdocstrings/typescript)
 [![gitter](https://badges.gitter.im/join%20chat.svg)](https://app.gitter.im/#/room/#typescript:gitter.im)
 
-A Typescript handler for mkdocstrings. :warning: **Work in progress** :warning:
+A Typescript handler for mkdocstrings.
+
+WARNING: **Still in prototyping phase!**
+Feedback is welcome.
 
 ## Installation
 

docs/insiders/goals.yml

@@ -13,3 +13,4 @@ goals:
     features:
     - name: "[Project] A TypeScript handler for mkdocstrings"
       ref: /
+      since: 2024/05/08