Docs updates for 64-bit multi-threaded Cannon

[pauldowman]

Cannon is undergoing a major refactor, it will support multi-threading and will become a 64-bit architecture instead of 32-bit.

This won't introduce any new sections into the docs but changes some details of sections that reference Cannon and op-challenger.

Here's a list of things that will be affected (incomplete - TODO)

• Details on the Cannon page (e.g. contract names), reference to single thread context
• Challenger command-line options (?)
• Breaking changes doc similar to this one
• TODO what else

[pauldowman]

@mbaxter @Inphi can you take a look at the checklist here and add general types of things that need documenting?

Or I'm also wondering if the changes are small and specific enough that the easiest thing might just be for one of you to go through the docs repo for any cannon references and just make a PR?

[Inphi]

The challenger cli options don't change. Otherwise, the list covers the docs changes. Specifically, the cannon page on docs.optimism.io should be updated.

[mbaxter]

There's also a page on MIPS.sol that looks like it should be updated.

[mbaxter]

Also, there's a relevant issue in the specs repo suggesting the MIPS.sol doc moves to the specs repo.

[pauldowman]

See also:

• https://github.com/ethereum-optimism/devrel/issues/440
• https://github.com/ethereum-optimism/devrel/issues/441