Merge pull request #1748 from buxx/add-game-open-combat

doc: update readme with open combat game

README.md

@@ -309,6 +309,7 @@ See also [crates matching keyword 'emulator'](https://crates.io/keywords/emulato
 
 See also [Games Made With Piston](https://github.com/PistonDevelopers/piston/wiki/Games-Made-With-Piston).
 
+* [buxx/OpenCombat](https://github.com/buxx/OpenCombat) - A realtime 2nd world war tactical game
 * [chess-tui](https://github.com/thomas-mauran/chess-tui) - A Chess TUI implementation ♟️
 * [citybound](https://github.com/citybound/citybound) - The city sim you deserve
 * [cristicbz/rust-doom](https://github.com/cristicbz/rust-doom) - A renderer for Doom, may progress to being a playable game