update instructions for wasm_command_bot example

examples/wasm_command_bot/README.md

@@ -1,10 +1,30 @@
 ## Example usage of matrix-rust-sdk from WASM
 
-You can build the example locally with:
+This example is a version of the
+[command bot](https://github.com/matrix-org/matrix-rust-sdk/tree/main/examples/command_bot)
+that runs as WASM in your browser instead of natively on your machine.
+
+To run this example, first ensure:
+
+1. The wasm-unknown-unknown target is available:
+   `rustup target add wasm32-unknown-unknown`.
+2. `wasm-pack` is in the path:
+   [see instructions here](https://rustwasm.github.io/wasm-pack/installer/).
+3. A homeserver is available at `http://localhost:8008` with a user `username`
+   and password `wordpass`. If this is not the case, you'll want to update these
+   connection settings in `src/lib.rs` before building.
+
+You can then build the example locally with:
 
     npm install
     npm run serve
 
 and then visiting http://localhost:8080 in a browser should run the example!
 
-This example is loosely based off of [this example](https://github.com/seanmonstar/reqwest/tree/master/examples/wasm_github_fetch), an example usage of `fetch` from `wasm-bindgen`.
+This example is loosely based off of
+[this example](https://github.com/seanmonstar/reqwest/tree/master/examples/wasm_github_fetch),
+an example usage of `fetch` from `wasm-bindgen`.
+
+NOTE: The webpage at `http://localhost:8080` will not display anything. It just
+runs the bot on the page, printing log messages to the console and responding to
+the `!party` command.