add Polymerium to launchers section (#42)

Co-authored-by: Pig Fang <g-plane@hotmail.com>

Author: d3ara1n

readme.md

@@ -248,6 +248,7 @@
 - [Prism](https://prismlauncher.org) - A fork of MultiMC, capable of downloading modpacks and other resources directly from CurseForge and FTB.
 - [HMCL](https://github.com/huanghongxun/HMCL) - A powered Minecraft launcher that supports a lot of features.
 - [XMCL](https://github.com/Voxelum/x-minecraft-launcher) - X Minecraft Launcher (XMCL) is a modern Minecraft launcher that lets you manage your massive resources like modpacks, resource packs, mods and shader packs.
+- [Polymerium](https://github.com/d3ara1n/Polymerium) - 🐿️ A next-generation Minecraft instance manager that thinks differently about game management.
 
 ## Development