Fix broken link to deployment script README in multisigTransactionPro…

[GarmashAlex]

This pr corrects the broken link in contracts/script/multisigTransactionProposals/README.md that previously pointed to a non-existent path (../../contracts/script/README.md). The link now correctly points to ../README.md, which contains the detailed instructions for setting up a Multisig Wallet and deploying the Light Client contract.