Update documentation links to Foundry's Scripting guide

[ericglau]

Update links from
https://book.getfoundry.sh/tutorials/solidity-scripting
to
https://book.getfoundry.sh/guides/scripting-with-solidity

in the following files:
https://github.com/OpenZeppelin/openzeppelin-foundry-upgrades/blob/main/README.md
https://github.com/OpenZeppelin/openzeppelin-foundry-upgrades/blob/main/docs/modules/pages/foundry-upgrades.adoc

Originally reported in:
OpenZeppelin/openzeppelin-upgrades#1130