Add OpenGMK On Emulator list

There's more

README.md

@@ -224,6 +224,8 @@ See also [crates matching keyword 'emulator'](https://crates.io/keywords/emulato
   * [mvdnes/rboy](https://github.com/mvdnes/rboy) — [![build badge](https://api.travis-ci.org/mvdnes/rboy.svg?branch=master)](https://travis-ci.org/mvdnes/rboy)
 * Gameboy Advance
   * [michelhe/rustboyadvance-ng](https://github.com/michelhe/rustboyadvance-ng) - RustboyAdvance-ng is a Gameboy Advance emulator with desktop, android and [WebAssembly](https://michelhe.github.io/rustboyadvance-ng/) support. [![build badge](https://github.com/michelhe/rustboyadvance-ng/workflows/Deploy/badge.svg?branch=master)](https://github.com/michelhe/rustboyadvance-ng/actions?query=workflow%3ADeploy)
+* GameMaker
+  * [OpenGMK](https://github.com/OpenGMK/OpenGMK) — OpenGMK is a modern rewrite of the proprietary GameMaker Classic engines, providing a full sourceport of the runner, a decompiler, a TASing framework, and libraries for working with gamedata yourself.
 * Intel 8080 CPU
   * [mohanson/i8080](https://github.com/mohanson/i8080) — Intel 8080 cpu emulator by Rust
 * NES