Add JavaScript embed docs

docs/source/features/embed.md

@@ -0,0 +1,8 @@
+# JavaScript Embed
+The [`vegafusion-wasm`](https://www.npmjs.com/package/vegafusion-wasm) NPM package provides a JavaScript API for embedding Vega charts backed by VegaFusion in web applications. These charts can be connected to a local VegaFusion runtime compiled to WebAssembly, or a remote VegaFusion server over gRPC-Web.
+
+## Usage
+See the [vegafusion-wasm README](https://github.com/vega/vegafusion/blob/v2/vegafusion-wasm/README.md) for usage instructions.
+
+## Demo
+See [editor demo](https://github.com/vega/vegafusion/tree/v2/examples/editor-demo) for a complete example.

docs/source/features/features.md

@@ -14,5 +14,6 @@ transform_extract
 chart_state
 inline_datasets
 grpc
+embed
 vega-lite
 ```

vegafusion-wasm/README.md

@@ -3,7 +3,7 @@ Wasm library for interfacing with VegaFusion.
 
 For more information, see the VegaFusion repository at https://github.com/hex-inc/vegafusion
 
-## Usage
+## gRPC-WebUsage
 Example usage with the VegaFusion server running locally on port 50051, with grpc-enabled:
 
 ```
@@ -31,11 +31,15 @@ let config = {
 let chart_handle = await vegaFusionEmbed(
     element,
     spec,  // Replace with your Vega spec
-    send_message_grpc,
     config,
+    send_message_grpc,
 );
 ```
 
+## Embedded Runtime Usage
+
+To use an embedded VegaFusion Runtime compiled with Web Assembly, simply omit the `send_message_grpc` argument from the `vegaFusionEmbed` call. In this configuration, the chart is fully self-contained and does not require a VegaFusion server.
+
 ## webpack config
 
 To use this library in a webpack project, you need to add the following [experimental options](https://webpack.js.org/configuration/experiments/) to your webpack config: