Clarify the pebble db path vs hash state scheme

[sbvegan]

Description

• Internally we have confirmed pebble/path works with full nodes, but we haven't really tested archive pebble/path nodes. All of our full nodes are configured that way.
• However we don't run any archive pebble/path nodes currently because they don't support all the functionality we need for archive rpc (specifically eth_getProof for historical blocks)

Acceptance criteria

User stories

Resources and support

• Slack thread

Action items

• Maybe add this information here: https://docs.optimism.io/chain-operators/reference/architecture or likely take information from that page and put more stuff in here: https://docs.optimism.io/chain-operators/guides/management/best-practices