mc: apply INIT/MAX RAM settings into FTB local settings file

fixes #222

minecraft-server/examples/docker-compose-ftb.yml

@@ -0,0 +1,16 @@
+version: '3.2'
+
+services:
+  mc:
+    image: itzg/minecraft-server
+    environment:
+      EULA: "true"
+      TYPE: FTB
+      FTB_SERVER_MOD: https://www.feed-the-beast.com/projects/ftb-presents-skyfactory-3/files/2481284
+    ports:
+      - 25565:25565
+    volumes:
+      - mc-ftb:/data
+
+volumes:
+  mc-ftb: