Cargo.toml: add more package metadata

Running cargo bitbake to generate a bitbake recipe currently results
in a few error messages due to missing metadata:

  No package.description set in your Cargo.toml, using package.name
  No package.homepage set in your Cargo.toml, trying package.repository
  error: No package.repository set in your Cargo.toml

Fill out these gaps and add some more related keys found while reading
through the documentation at [1].

[1]: https://doc.rust-lang.org/cargo/reference/manifest.html

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

Cargo.toml

@@ -3,6 +3,12 @@ name = "rsinit"
 version = "0.1.0"
 edition = "2021"
 license = "GPL-2.0-only"
+description = "minimalistic single binary initramfs init for embedded systems"
+homepage = "https://github.com/michaelolbrich/rsinit"
+repository = "https://github.com/michaelolbrich/rsinit"
+keywords = ["initramfs", "init", "rdinit"]
+categories = ["embedded"]
+readme = "README.md"
 
 [[bin]]
 name = "init"