docs: added example of auto-cf custom manifest (#2582)

examples/auto-cf/modpack-manifest/docker-compose.yml

@@ -0,0 +1,19 @@
+services:
+  mc:
+    image: itzg/minecraft-server
+    environment:
+      EULA: true
+      MOD_PLATFORM: AUTO_CURSEFORGE
+      # allocate from https://console.curseforge.com/ and set in .env file
+      CF_API_KEY: ${CF_API_KEY}
+      CF_MODPACK_MANIFEST: /manifests/manifest.json
+      CF_SLUG: "custom"
+      MEMORY: 2G
+    volumes:
+      - mc-data:/data
+      - ./manifests:/manifests:ro
+    ports:
+      - "25565:25565"
+
+volumes:
+  mc-data: {}

examples/auto-cf/modpack-manifest/manifests/manifest.json

@@ -0,0 +1,28 @@
+{
+  "minecraft": {
+    "version": "1.20.4",
+    "modLoaders": [
+      {
+        "id": "fabric-0.15.3",
+        "primary": true
+      }
+    ]
+  },
+  "manifestType": "minecraftModpack",
+  "manifestVersion": 1,
+  "name": "Custom",
+  "author": "",
+  "files": [
+    {
+      "projectID": 351725,
+      "fileID": 4973035,
+      "required": true
+    },
+    {
+      "projectID": 306612,
+      "fileID": 5010374,
+      "required": true
+    }
+  ],
+  "overrides": "overrides"
+}