[tut] How do we handle frontier & ink-contract tutorials?

[jimmychu0807]

I recommended:

• For frontier tutorial, port over to substrate-docs
• For ink-contract tutorial, if confirmed ink! team want to handle it themselves, we may want to transfer it back under paritytech github organization.

Otherwise, it is going to be disappear when substrate.dev got shutdown.

[jimmychu0807]

There are 2 tickets: #24 #45 cover this already.