feat readme: progress and examples

README.md

@@ -2,12 +2,59 @@
 
 [![MIT licensed](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/edouardparis/rust-lnurl/blob/master/LICENSE)
 
-[lnurl specs](https://github.com/btcontract/lnurl-rfc/blob/master/spec.md)
-
 ## Documentation
 
 _Readings about **lnurl**_
 
 
 * [The spec](https://github.com/btcontract/lnurl-rfc/blob/master/spec.md) – **lnurl** spec, by [Anton Kumaigorodski](https://twitter.com/akumaigorodski).
 * [An introduction to lnurl](https://telegra.ph/lnurl-a-protocol-for-seamless-interaction-between-services-and-Lightning-wallets-08-19) – An article introducing the various types of **lnurl**'s, by [fiatjaf](https://twitter.com/fiatjaf).
+
+## Progress
+
+- [x] lnurl-withdraw
+- [ ] lnurl-auth
+- [ ] lnurl-pay
+- [ ] lnurl-channel
+
+## Usage
+
+You will certainly need some crates like:
+```toml
+bech32 = "0.7.1"
+lightning-invoice = "0.2.0"
+serde = { version = "1.0.93", features =["derive"]}
+serde_json = "1.0.39"
+```
+
+Create a bech32 QRCode:
+```rust
+use bech32::ToBase32;
+use image::Luma;
+use qrcode::QrCode;
+
+pub fn create_lnurl_qrcode(url: &str, path: &str) {
+    let encoded = bech32::encode("lnurl", url.as_bytes().to_base32()).unwrap();
+    let code = QrCode::new(encoded.to_string()).unwrap();
+    let image = code.render::<Luma<u8>>().build();
+    image.save(path).unwrap();
+}
+```
+
+Use serde_json to encode your LNRUL object in the HTTP response body
+of your server.
+
+```rust
+if let Err(_) = invoice.parse::<lightning_invoice::SignedRawInvoice>() {
+    let res = serde_json::to_string(
+        &lnurl::Response::Error{reason: "your invoice is wrong".to_string()}
+    ).unwrap();
+    return Ok(Response::builder()
+        .status(StatusCode::BAD_REQUEST)
+        .header(header::CONTENT_TYPE, "application/json")
+        .body(Body::from(res)).unwrap())
+}
+```
+
+See [lnurl-examples](https://github.com/edouardparis/lnurl-examples)
+