wasm: Add a minimal README

Author: shesek

src/wasm_package/README.md

@@ -0,0 +1,29 @@
+# libwally JS
+
+WASM-based JavaScript bindings for [libwally](https://github.com/elementsproject/libwally-core),
+for nodejs and the browser.
+
+## Installation
+
+```bash
+$ npm install wallycore
+```
+
+## Example use
+
+```js
+import wally from 'wallycore'
+
+const word = wally.bip39_get_word(null, 10)
+
+const script = wally.address_to_scriptpubkey("1EMBaSSyxMQPV2fmUsdB7mMfMoocgfiMNw", wally.WALLY_NETWORK_BITCOIN_MAINNET)
+
+const tx = wally.tx_from_hex('020000...', 0)
+console.log(wally.tx_get_txid(tx).toString('hex))
+wally.tx_free(tx)
+```
+
+If you're using CommonJS, the module can be loaded asynchronously using `const wally = await import('wallycore')` or `import('wallycore').then(wally => { ... })`.
+
+## License
+[BSD/MIT](https://github.com/ElementsProject/libwally-core/blob/master/LICENSE)