message: Enable doc_cfg on doc.rs builds
diff: #![cfg_attr(feature = "cargo-clippy", allow(clippy::missing_panics_doc))]
  #![cfg_attr(all(feature = "cargo-clippy", test), allow(clippy::cyclomatic_complexity))]
  #![cfg_attr(not(test), allow(dead_code))]
  +// To build docs locally:
  +// RUSTDOCFLAGS="--cfg docsrs" cargo +nightly doc --features blosc,lzf
  +#![cfg_attr(docsrs, feature(doc_cfg))]
  #[cfg(all(feature = "mpio", not(h5_have_parallel)))]
  compile_error!("Enabling \"mpio\" feature requires HDF5 library built with MPI support");
  