Add archival notice to readme

This repo is about to be archived, it turns out we don't want to do
this.

README.md

@@ -1,3 +1,8 @@
+**This was an exploratory crate that turned out not to be useful, the
+repository is being archived and this crate should not be used**
+
+If you would like to use the crate name, reach out to me.
+
 # Rust Cryptographic Hash Functions.
 
 This is a simple, minimal-dependency library which implements the bunch of crypotographic hash

src/internal_macros.rs

@@ -2,19 +2,6 @@
 
 //! Non-public macros
 
-/// Adds `AsRef` implementation to a given type `$ty`.
-macro_rules! as_ref_impl(
-    ($ty:ident) => (
-        $crate::internal_macros::as_ref_impl!($ty, );
-    );
-    ($ty:ident, $($gen:ident: $gent:ident),*) => (
-        impl<$($gen: $gent),*> $crate::_export::_core::convert::AsRef<[u8]> for $ty<$($gen),*>  {
-            fn as_ref(&self) -> &[u8] { &self[..] }
-        }
-    )
-);
-pub(crate) use as_ref_impl;
-
 /// Adds an implementation of the `HashEngine::input` method.
 macro_rules! engine_input_impl(
     ($n:literal) => (