Add volume mount for geth data (#49)

* Add volume mount for geth data

Persist chain data

* Add geth-data to .gitignore

---------

Co-authored-by: Michael de Hoog <michael.dehoog@coinbase.com>

Author: Freekers

.gitignore

@@ -1 +1,2 @@
 /.idea/
+/geth-data/

docker-compose.yml

@@ -6,6 +6,8 @@ services:
       - 8546:8546
       - 30303:30303
     command: [ "sh", "./geth-entrypoint" ]
+    volumes:
+      - "./geth-data:/data"
     environment:
       - OP_GETH_GENESIS_FILE_PATH=goerli/genesis-l2.json
       - OP_GETH_SEQUENCER_HTTP=https://goerli.base.org