Add Machinery (h4cc#4417)

README.md

@@ -151,6 +151,7 @@ There are [other sites with curated lists of elixir packages](#other-awesome-lis
 * [loom](https://github.com/asonge/loom) - A CRDT library with δ-CRDT support.
 * [luhn](https://github.com/ma2gedev/luhn_ex) - Luhn algorithm in Elixir.
 * [lz4](https://github.com/szktty/erlang-lz4) - LZ4 bindings for Erlang for fast data compressing.
+* [machinery](https://github.com/joaomdmoura/machinery) - A state machine library for structs in general, it integrates with Phoenix out of the box.
 * [memoize](https://github.com/os6sense/DefMemo) - A memoization macro (defmemo) for elixir using a genserver backing store.
 * [merkle_tree](https://github.com/yosriady/merkle_tree) - A Merkle hash tree implementation in Elixir.
 * [minmaxlist](https://github.com/seantanly/elixir-minmaxlist) - Elixir library extending `Enum.min_by/2`, `Enum.max_by/2` and `Enum.min_max_by/2` to return a list of results instead of just one.