Flashblocks Rollup Boost Design Doc

[dmarzzz]

Add internal design document to docs repo in this repo. (design document has been internal solely because we're iterating and didn't want to confuse)

Will be nice to give system-level view (op-node, op-geth, batcher, RPC provider) and which parties need to run forked software

[0xKitsune]

Bumping this to see if there are any docs that should be added to the repo or if we can close this issue.