Merge #870: docs: fix broken link

573fb55 docs: fix broken link (radik878)

Pull request description:

  https://blog.rust-lang.org/2020/02/27/Rust-1.56.1.html - old
  https://blog.rust-lang.org/2022/08/11/Rust-1.63.0/"><img alt="Rustc Version 1.63.0+ - new, actual
  reopen #869


ACKs for top commit:
  apoelstra:
    ACK 573fb55; successfully ran local tests


Tree-SHA512: 401366e6fb2f422ddfa79e235b5c00403edaabd2c521f5ad394e769f410870d3cf56f6f79c1d328c75dada4778deed4e836eff99a63f0742398b556f5cac95bf

Author: apoelstra

secp256k1-sys/README.md

@@ -5,7 +5,7 @@
     <a href="https://crates.io/crates/secp256k1-sys"><img alt="Crate Info" src="https://img.shields.io/crates/v/secp256k1-sys.svg"/></a>
     <a href="https://github.com/rust-bitcoin/rust-secp256k1/blob/master/LICENSE"><img alt="CC0 1.0 Universal Licensed" src="https://img.shields.io/badge/license-CC0--1.0-blue.svg"/></a>
     <a href="https://docs.rs/secp256k1-sys"><img alt="API Docs" src="https://img.shields.io/badge/docs.rs-secp256k1--sys-green"/></a>
-    <a href="https://blog.rust-lang.org/2020/02/27/Rust-1.56.1.html"><img alt="Rustc Version 1.56.1+" src="https://img.shields.io/badge/rustc-1.56.1%2B-lightgrey.svg"/></a>
+    <a href="https://blog.rust-lang.org/2022/08/11/Rust-1.63.0/"><img alt="Rustc Version 1.63.0+" src="https://img.shields.io/badge/rustc-1.63.0%2B-lightgrey.svg"/></a>
   </p>
 </div>