Update readme with more details about the language and extension

- [ ] should add details on what the extension can do for the user
- [ ] coloration
- [ ] snippets (soon? see #3)
- [ ] auto-completion from code/std lib (soon?)
- [ ] describe the language briefly, the team, where to get it, links to the website and documentation

Start by reading the current README and issue #3 for the planned snippets context. Update the README with the extension’s coloration, snippets and auto-completion details, then add a brief language and team description plus links to the language website and documentation. Done means all checklist items are addressed.

Written by the indexing model from the issue text.