Add docs.rs documentation link to cxx-build's Cargo.toml

Author: Enyium

gen/build/Cargo.toml

@@ -4,6 +4,7 @@ version = "1.0.88"
 authors = ["David Tolnay <[email protected]>"]
 categories = ["development-tools::build-utils", "development-tools::ffi"]
 description = "C++ code generator for integrating `cxx` crate into a Cargo build."
+documentation = "https://docs.rs/cxx-build"
 edition = "2018"
 exclude = ["build.rs"]
 homepage = "https://cxx.rs"