Add multisig rust tutorial

### Feature description

We should add a "how to" example of how to set up the multisig.

### Why is this feature needed?

_No response_

Look at existing tutorials in the repository to understand the format and structure. The tutorial should explain how to set up a multisig, likely involving cryptographic signatures and transaction logic. Check for any existing multisig examples or related code in the 0xMiden ecosystem to reference. The deliverable is a new tutorial document that walks through the steps clearly.

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