message: docs: clarify where package metadata comes from
diff: @@ -61,9 +61,9 @@ let version = env!("CARGO_PKG_VERSION");
  * `CARGO_PKG_VERSION_PRE` - The pre-release version of your package.
  * `CARGO_PKG_AUTHORS` - Colon separated list of authors from the manifest of your package.
  * `CARGO_PKG_NAME` - The name of your package.
  -* `CARGO_PKG_DESCRIPTION` - The description of your package.
  -* `CARGO_PKG_HOMEPAGE` - The home page of your package.
  -* `CARGO_PKG_REPOSITORY` - The repository of your package.
  +* `CARGO_PKG_DESCRIPTION` - The description from the manifest of your package.
  +* `CARGO_PKG_HOMEPAGE` - The home page from the manifest of your package.
  +* `CARGO_PKG_REPOSITORY` - The repository from the manifest of your package.
  * `OUT_DIR` - If the package has a build script, this is set to the folder where the build
  script should place its output. See below for more information.
  