Add ability / instructions to sync / create test rETH node data

[liangjh]

Referencing TG convo in paradigm_reth room -- add ability for users to test and develop using reth-indexer without having to create / run a full or archive rETH node. this could take a form of: (a) a small database / datadump, (b) a generator to create some fake data, or (3) links or setup instructions on standing up a minimally viable rETH node with much smaller requirements than the current 2TB requirement for archive nodes.

https://t.me/paradigm_reth/9337