Add example fabric mod

src/main/java/com/example/mixin/ExampleMixin.java

@@ -0,0 +1,15 @@
+package com.example.mixin;
+
+import net.minecraft.server.MinecraftServer;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+@Mixin(MinecraftServer.class)
+public class ExampleMixin {
+	@Inject(at = @At("HEAD"), method = "loadWorld")
+	private void init(CallbackInfo info) {
+		// This code is injected into the start of MinecraftServer.loadWorld()V
+	}
+}