build: establish Tree Feller project

src/main/java/games/dmg/treefeller/TreeFellerPlugin.java

@@ -0,0 +1,11 @@
+package games.dmg.treefeller;
+
+import org.bukkit.plugin.java.JavaPlugin;
+
+/** Entry point for Tree Feller. */
+public final class TreeFellerPlugin extends JavaPlugin {
+    @Override
+    public void onEnable() {
+        saveDefaultConfig();
+    }
+}