Carify what the maintainace policy is on this repo

[nuke-web3]

these examples are at various versions of the RISC Zero tools. Mnay users are very eager to use these with modern, ideally uniform versions.

Are all demos going to be maintained? In any case the READMEs here should have a notice about this IMHO

[pdg744]

The intent of this repo is to have a place where we can release demos that we aren't planning to diligently maintain. People who want to use these demos will need to check out the appropriate version of the zkVM in order to do so.

We should be explicit in the README for each demo that users will need to check out a specific version. I've addressed that in #32, which IMO is sufficient action to close this issue.

WDYT @nuke-web3?

[pdg744]

We might also want to open issues to update the demos to use the current version of the zkVM.
And perhaps mark them as help wanted.