Remove redundant configuration from Cargo.toml

`documentation` is no longer needed since docs.rs is now automatically
linked, and the Cargo docs say that `homepage` should not be redundant
with `repository`.

Author: tgross35

Cargo.toml

@@ -5,8 +5,6 @@ authors = ["Alex Crichton <[email protected]>"]
 license = "MIT OR Apache-2.0"
 readme = "README.md"
 repository = "https://github.com/rust-lang/cfg-if"
-homepage = "https://github.com/rust-lang/cfg-if"
-documentation = "https://docs.rs/cfg-if"
 description = """
 A macro to ergonomically define an item depending on a large number of #[cfg]
 parameters. Structured like an if-else chain, the first matching branch is the