message: Update readme with new version and observable instructions.
diff: ## Basic Example
  -You can import Vega-Embed from a local copy or (as shown below) [from jsDelivr](hhttps://www.jsdelivr.com/package/npm/vega-embed). Please replace `[VERSION]` with the correct [Vega](https://www.jsdelivr.com/package/npm/vega), [Vega-Lite](https://www.jsdelivr.com/package/npm/vega-lite), and [Vega-Embed](https://www.jsdelivr.com/package/npm/vega-embed) versions. We recommend that you specify the major versions (`vega@4`, `vega-lite@3`, `vega-embed@3`).
  +You can import Vega-Embed from a local copy or (as shown below) [from jsDelivr](hhttps://www.jsdelivr.com/package/npm/vega-embed). Please replace `[VERSION]` with the correct [Vega](https://www.jsdelivr.com/package/npm/vega), [Vega-Lite](https://www.jsdelivr.com/package/npm/vega-lite), and [Vega-Embed](https://www.jsdelivr.com/package/npm/vega-embed) versions. We recommend that you specify the major versions (`vega@5`, `vega-lite@3`, `vega-embed@4`).
  ```html
  <!DOCTYPE html>
  <html>
  <head>
  - <!-- Import Vega 4 & Vega-Lite 3 (does not have to be from CDN) -->
  + <!-- Import Vega 5 & Vega-Lite 3 (does not have to be from CDN) -->
  <script src="https://cdn.jsdelivr.net/npm/vega@[VERSION]"></script>
  <script src="https://cdn.jsdelivr.net/npm/vega-lite@[VERSION]"></script>
  <!-- Import vega-embed -->
  @@ -46,6 +46,9 @@ You can import Vega-Embed from a local copy or (as shown below) [from jsDelivr](
  Look at an example online at [Vega-Embed Block](https://bl.ocks.org/domoritz/455e1c7872c4b38a58b90df0c3d7b1b9).
  +## Use Vega-Embed in Observable
  +
  +You can require embed with `embed = require('vega-embed@4')` and then embed a chart with `viewof view = embed(...)`. Check the [our example notebook](https://beta.observablehq.com/@domoritz/hello-vega-embed) for more details.
  ## API Reference
  