fix(docker): Document MongoDB disk space issue and solutions

backend/docker-compose.dev.yml

@@ -31,7 +31,14 @@ services:
     environment:
       - MONGO_INITDB_DATABASE=normogen_dev
     volumes:
+      # Option 1: Use named volume (default)
       - mongodb_dev_data:/data/db
+      
+      # Option 2: Use host directory with more space
+      # - /path/to/more/space/mongodb:/data/db
+      
+      # Option 3: Use tmpfs (WARNING: data is lost on container stop!)
+      # - mongodb_tmp:/data/db
     networks:
       - normogen-network
     healthcheck:
@@ -43,6 +50,12 @@ services:
 volumes:
   mongodb_dev_data:
     driver: local
+  # For Option 3 (tmpfs):
+  # mongodb_tmp:
+  #   driver: local
+  #   driver_opts:
+  #     type: tmpfs
+  #     device: tmpfs
 networks:
   normogen-network:
     driver: bridge