feat: add sharmir demo

__crypto/shamir-demo/src/main.rs

@@ -0,0 +1,16 @@
+use shamir::SecretData;
+
+fn main() {
+    let secret_data = SecretData::with_secret("Hello World!", 3);
+
+    let share1 = secret_data.get_share(1).unwrap();
+    let share2 = secret_data.get_share(2).unwrap();
+    let share3 = secret_data.get_share(3).unwrap();
+    let share4 = secret_data.get_share(4).unwrap();
+
+    println!("{:?}\n{:?}\n{:?}\n{:?}", share1, share2, share3, share4);
+    let recovered = SecretData::recover_secret(3, vec![share1, share2, share3]).unwrap();
+
+    println!("Recovered: {}", recovered);
+}
+