Add foundry multisig guide

[a-zorina]

Title

Add Foundry Multisig guide.

Description

Adds a beginner-friendly tutorial for building a minimally functional Multisig on Rootstock using Foundry to the Resources/Tutorials section.

Screenshots/GIFs

Testing

yarn build showed no issues related to the added file.

Checklist

• I have read and understood the contributing guidelines.
• I have followed the style guide and formatting guidelines.
• I have added appropriate comments to explain the changes.
• I have tested my changes thoroughly.

Refs

• Related links to issues, tickets, etc.

[vercel]

@a-zorina is attempting to deploy a commit to the IOV Labs Team on Vercel.

A member of the Team first needs to authorize it.

[owans]

Hi @a-zorina,

Thank you for your contribution, currently reviewing the guide.

Could you add a ref to this content in the tutorial index.md?

Thank you