some docs updates I missed (#39)

Cargo.toml

@@ -1,12 +1,12 @@
 [package]
 authors = ["Jason Ozias <jason.g.ozias@gmail.com>"]
 categories = ["development-tools", "development-tools::build-utils"]
-description = "Generate version related functions"
+description = "Generate build, git, and rustc related 'cargo:rustc-env' instructions via 'build.rs' for use in your code via the env! macro"
 documentation = "http://docs.rs/vergen"
 edition = "2018"
 homepage = "http://github.com/rustyhorde/vergen"
-keywords = ["version", "generation"]
-license = "MIT/Apache-2.0"
+keywords = ["cargo", "instructions", "semver", "git", "build.rs"]
+license = "MIT OR Apache-2.0"
 name = "vergen"
 readme = "README.md"
 repository = "https://github.com/rustyhorde/vergen"

src/lib.rs

@@ -56,7 +56,10 @@
 //! #..
 //!
 //! [build-dependencies]
-//! vergen = "3"
+//! vergen = "4"
+//! # or
+//! vergen = { version = "4", default-features = false, features = ["build", "rustc"] }
+//! # if you wish to disable certain features
 //! ```
 //!
 //! ### build.rs