8ccfb412c1 Improve documentation of `hash_newtype!` (Martin Habovstiak)
58876e2be9 Remove unused macro (Martin Habovstiak)
Pull request description:
Removed unused macro and improved documentation to address review of #1659 - see commits. I also added a note about recursion.
ACKs for top commit:
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tcharding:
ACK 8ccfb412c1
Tree-SHA512: 3b4b0c4ffc8a5166619110d9dcb51affd5cafbb2af84a55dd540a815e4702514d99c71dc1c54aca27fb91970e7e7189d1dffb4f7da7951b0f71336ef6f32d30b