add readme

Cargo.toml

@@ -5,6 +5,7 @@ edition = "2021"
 authors = ["jmic <jmic@users.noreply.github.com>"]
 description = "Community implementation of the Altcha library in Rust for your own server applications to create and validate challenges and responses."
 license = "Apache-2.0"
+readme = "README.md"
 
 [lib]
 path = "src/lib.rs"

README.md

@@ -0,0 +1,44 @@
+# Community ALTCHA Rust Library   [![Build & test](https://github.com/jmic/altcha-lib-rs/actions/workflows/build-and-test.yml/badge.svg)](https://github.com/jmic/altcha-lib-rs/actions/workflows/build-and-test.yml)
+
+**Community implementation of the Altcha library in Rust for your
+own server applications to create and validate challenges and responses.**
+
+---
+
+## Setup
+
+```toml
+[dependencies]
+altcha-lib-rs = { version = "1.0", features = ["json"] }
+```
+
+## Example
+
+```rust
+use altcha_lib_rs::{create_challenge, verify_json_solution, 
+                    Payload, Challenge, ChallengeOptions};
+
+// create a challenge
+let challenge = create_challenge(ChallengeOptions {
+    hmac_key: "super-secret",
+    expires: Some(Utc::now() + chrono::TimeDelta::minutes(1)),
+    ..Default::default()
+}).expect("should be ok");
+
+// transmit the challenge to the client and let the clint solve it
+let res = solve_challenge(&challenge.challenge, &challenge.salt, None, None, 0)
+    .expect("need to be solved");
+// pack the solution into a json string
+let payload = Payload {
+    algorithm: challenge.algorithm,
+    challenge: challenge.challenge,
+    number: res,
+    salt: challenge.salt,
+    signature: challenge.signature,
+    took: None,
+};
+let string_payload = serde_json::to_string(&payload).unwrap();
+
+// receive the solution from the client and verify it
+verify_json_solution(&string_payload, "super-secret", true).expect("should be verified");
+```