message: document hdf5-types and crate features
diff: #![recursion_limit = "1024"]
  #![cfg_attr(feature = "cargo-clippy", allow(clippy::missing_safety_doc))]
  +//! Types that can be stored and retrieved from a `HDF5` dataset
  +//!
  +//! Crate features:
  +//! * `const_generics`: Uses const generics to enable arrays [T; N] for all N.
  +//! Compiling without this limits arrays to certain prespecified
  +//! sizes
  +
  #[cfg(test)]
  #[macro_use]
  extern crate quickcheck;
  