Merge pull request #557 from ariard/2020-03-link-arch-md

Link ARCH.md in README.md

Author: TheBlueMatt

README.md

@@ -46,6 +46,6 @@ Contributors are warmly welcome, see [CONTRIBUTING.md](CONTRIBUTING.md).
 Project Architecture
 ---------------------
 
-COMING SOON.
+For a Rust-Lightning high-level API introduction, see [ARCH.md](ARCH.md).
 
 License is Apache-2.0.