Add repository in Cargo.toml (#242)

Adding the repository in the Cargo.toml file will give greater
accessability to this Crate's source code to its users.

Closes #235

Author: Riceman2000

cloudflare/Cargo.toml

@@ -2,6 +2,7 @@
 name = "cloudflare"
 version = "0.12.0"
 authors = ["Noah Kennedy <nkennedy@cloudflare.com>", "Jeff Hiner <jhiner@cloudflare.com>"]
+repository = "https://github.com/cloudflare/cloudflare-rs"
 edition = "2018"
 description = "Rust library for the Cloudflare v4 API"
 keywords = ["cloudflare", "api", "client"]