Update base fee mentions

[cpengilly]

Flagging that throughout docs there’s some mentions that the OP minimum base fee is “1 gwei” when it should be “1 wei.” Other data people are confused and think we have some in protocol base fee floor, when we don’t.

https://docs.optimism.io/builders/chain-operators/management/configuration#eip-1559-gas-algorithm

https://docs.optimism.io/stack/transactions/fees#base-fee

Per M. Silberling:  if it’s initialized at 1 gwei, we should maybe call out that that doesn’t mean it’s the minimum