examples: add bentobox example using DOWNLOAD_EXTRA_CONFIGS (#3708)

examples/bentobox/compose.yml

@@ -0,0 +1,22 @@
+services:
+  mc:
+    image: itzg/minecraft-server
+    environment:
+      EULA: "TRUE"
+      TYPE: PAPER
+      DEBUG: true
+      PLUGINS: |
+        https://download.geysermc.org/v2/projects/geyser/versions/latest/builds/latest/downloads/spigot
+        https://download.geysermc.org/v2/projects/floodgate/versions/latest/builds/latest/downloads/spigot
+        https://hangarcdn.papermc.io/plugins/BentoboxWorld/bentobox/versions/3.7.4/PAPER/BentoBox-3.7.4.jar
+      DOWNLOAD_EXTRA_CONFIGS: |
+        # Even though it's a jar can be treated just like any other file
+        plugins/BentoBox/addons<https://github.com/BentoBoxWorld/AOneBlock/releases/download/1.20.0/AOneBlock-1.20.0.jar
+    ports:
+      - "25565:25565"
+      - "25565:25565/udp"
+      - "19132:19132/udp"
+    volumes:
+      - data:/data
+volumes:
+  data: