chore: set index cache size to 2G

docker-compose.yml

@@ -4,6 +4,8 @@ services:
     container_name: ord
     network_mode: host
     restart: always
+    environment:
+      INDEX_CACHE_SIZE: 2097152
     command: --chain mainnet --config-dir /var/lib/ord --datadir /var/lib/ord --index-addresses --index-runes --index-sats --commit-interval 100 --bitcoin-rpc-url ${BITCOIN_RPC_URL} --bitcoin-rpc-username ${BITCOIN_RPC_USERNAME} --bitcoin-rpc-password ${BITCOIN_RPC_PASSWORD} server --http --http-port ${ORD_PORT}
     volumes:
       - $PWD/data:/var/lib/ord