Add instructions to README for using crate and publishing (#93)

* Add instructions to README for using crate and publishing

* Move publish into a script

crates/quickjs-wasm-rs/README.md

@@ -27,3 +27,17 @@ let input_value = messagepack::transcode_input(&context, input_bytes).unwrap();
 let output_value: Value = ...;
 let output = messagepack::transcode_output(output_value).unwrap();
 ```
+
+## Building a project using this crate
+
+- Install the [wasi-sdk](https://github.com/WebAssembly/wasi-sdk#install) for your platform
+- Set the `QUICKJS_WASM_SYS_WASI_SDK_PATH` environment variable to the absolute path where you installed the `wasi-sdk`
+
+For example, if you install the `wasi-sdk` in `/opt/wasi-sdk`, you can run:
+```bash
+export QUICKJS_WASM_SYS_WASI_SDK_PATH=/opt/wasi-sdk
+```
+
+## Publishing to crates.io
+
+To publish this crate to crates.io, run `./publish.sh`.

crates/quickjs-wasm-rs/publish.sh

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+
+set -e
+
+if [[ -z $QUICKJS_WASM_SYS_WASI_SDK_PATH ]]; then
+    echo "QUICKJS_WASM_SYS_WASI_SDK_PATH must be set to a path with a downloaded wasi-sdk" 1>&2
+    exit 1
+fi
+
+cargo publish --target=wasm32-wasi