cargo-rbmt: beef up manifest metadata

Author: nyonson

cargo-rbmt/Cargo.toml

@@ -2,6 +2,10 @@
 name = "cargo-rbmt"
 version = "0.1.0"
 authors = ["Nick Johnson <nick@yonson.dev>"]
+description = "Maintainer tools for rust-bitcoin projects"
+repository = "https://github.com/rust-bitcoin/rust-bitcoin-maintainer-tools"
+keywords = ["bitcoin"]
+categories = ["development-tools::cargo-plugins"]
 license = "CC0-1.0"
 edition = "2021"
 rust-version = "1.85.0"