* Check existing L1 contracts deployment
* Rename volume used for generated L2 config
* Check for existing L2 geth data directory
* Cross check existing L2 config against L1 deployment config
* Verify sequencer key in existing L2 geth data directory
* Add instructions to troubleshoot corrupt L2 geth dir
* Separate out instructions to run L2 with external L1
* Update docs
Former-commit-id: 9ffa9bb5a9
