Fix readme field in Cargo.toml
@@ -5,7 +5,7 @@ authors = ["The Portier project contributors"]
description = "Reference implementation of the Portier broker protocol"
homepage = "http://portier.io"
repository = "https://github.com/portier/portier-broker"
-readme = "README.rst"
+readme = "README.md"
license = "MIT/Apache-2.0"
edition = "2018"
