Add Mk48.io game

At the time of writing, it has 72 GitHub stars. Because all of the game's client & server source code, assets, and infrastructure-as-code scripts are open source, the game has decent utility to the Rust community.

README.md

@@ -229,6 +229,7 @@ See also [Games Made With Piston](https://github.com/PistonDevelopers/piston/wik
 * [rhex](https://github.com/dpc/rhex) — hexagonal ascii roguelike
 * [rsaarelm/magog](https://github.com/rsaarelm/magog) — A roguelike game in Rust
 * [schulke-214/rsnake](https://github.com/schulke-214/rsnake) — Snake written in Rust.
+* [SoftbearStudios/mk48](https://github.com/SoftbearStudios/mk48) — Mk48.io is an online multiplayer naval combat game
 * [swatteau/sokoban-rs](https://github.com/swatteau/sokoban-rs) — A Sokoban implementation
 * [thetawavegame/thetawave-legacy](https://github.com/thetawavegame/thetawave-legacy) - A space shooter game that strives to be an entry point for new game developers to make their first contributions. ![build badge](https://github.com/thetawavegame/thetawave-legacy/actions/workflows/ci.yml/badge.svg?branch=master)
 * [Thinkofname/rust-quake](https://github.com/Thinkofname/rust-quake) — Quake map renderer in Rust