message: Fix the documentation for the PROFILE envvar passed to build scripts
  Closes
diff: @@ -84,8 +84,7 @@ let out_dir = env::var("OUT_DIR").unwrap();
  be useful to pass a `-j` parameter to a system like `make`.
  * `OPT_LEVEL`, `DEBUG` - values of the corresponding variables for the
  profile currently being built.
  -* `PROFILE` - name of the profile currently being built (see
  - [profiles][profile]).
  +* `PROFILE` - `release` for release builds, `debug` for other builds.
  * `DEP_<name>_<key>` - For more information about this set of environment
  variables, see build script documentation about [`links`][links].
  * `RUSTC`, `RUSTDOC` - the compiler and documentation generator that Cargo has
  