expanded README (#1305)

Author: mbostock

README.md

@@ -1,5 +1,23 @@
 # Observable Framework
 
-- [Documentation](https://observablehq.com/framework/)
-- [Changelog](https://github.com/observablehq/framework/releases)
-- [Issues](https://github.com/observablehq/framework/issues)
+[**Observable Framework**](https://observablehq.com/framework/) is a free, [open-source](./LICENSE), static site generator for data apps, dashboards, reports, and more. Framework combines JavaScript on the front-end for interactive graphics with any language on the back-end for data analysis. Framework features [data loaders](https://observablehq.com/framework/loaders) that precompute static snapshots of data at build time for dashboards that load instantly.
+
+## Documentation 📚
+
+https://observablehq.com/framework/
+
+## Examples 🖼️
+
+https://github.com/observablehq/framework/tree/main/examples
+
+## Releases (changelog) 🚀
+
+https://github.com/observablehq/framework/releases
+
+## Getting help 🏠
+
+Please [open a discussion](https://github.com/observablehq/framework/discussions) if you’d like help. We also recommend [searching issues](https://github.com/observablehq/framework/issues). You can also ask on the [Observable forum](https://talk.observablehq.com/) or [Observable community Slack](https://observablehq.com/slack/join).
+
+## Contributing 🙏
+
+See [`CONTRIBUTING.md`](./CONTRIBUTING.md).