Add mainnet bootup docker instructions to README

README.md

@@ -136,6 +136,27 @@ NixOS users can also use the [NixOS service](https://cardano-foundation.github.i
     - 200GB of disk space: the history
     - 24GB of RAM: the utx set in the node process heap
 
+You can download a snapshot to speed up the synchronization process, but you will
+give up the trustless nature of the blockchain, as a malicious initial block producer
+could have been forging this. TO BE CONFIRMED!! @Heinrich
+
+```bash
+cd run/mainnet/docker
+./snapshot.sh
+```
+
+The snapshot.sh will try to use `NODE_DB` as the directory to store the snapshot.
+
+If you did it or not you can start the wallet with
+
+```bash
+cd run/mainnet/docker
+# necessary to patch the wallet arguments
+export DOCKER_COMPOSE_FILE=docker-compose.yml:mainnet-compose.yml
+./run.sh start
+```
+
+
 ### Running on preprod
 
 Preprod network is broken for node 9.0.0 at some block in the past.