docs: add readme (#1)

.github/README.md

@@ -1,3 +1,11 @@
 <h1 style="text-align: center">ADR36</h1>
 
-[![codecov](https://img.shields.io/codecov/c/gh/noble-assets/adr36?token=4MKPLURKGG&labelColor=black)](https://codecov.io/gh/noble-assets/adr36)
+[![codecov](https://img.shields.io/codecov/c/gh/noble-assets/adr36?token=4MKPLURKGG&labelColor=black)](https://codecov.io/gh/noble-assets/adr36) [![license](https://img.shields.io/github/license/noble-assets/adr36?labelColor=black)](../LICENSE)
+
+[ADR36] is a standard within the Cosmos ecosystem that defines the structure of
+signing arbitrary data for Cosmos SDK-based chains. It enables users to
+authenticate and authorize actions by signing messages off-chain using their
+private keys. The signed messages can be verified on-chain or off-chain,
+ensuring that actions are genuinely initiated by the holder.
+
+[adr36]: https://docs.cosmos.network/v0.50/build/architecture/adr-036-arbitrary-signature