Certora Script Update & Minor changes

[remedcu]

Fixes #468

This PR eliminates the use of a script for the Certora FV and uses the Certora CLI command directly.

In addition, extra small changes included in this PR:

• Natspec changes in Harness solidity code.
• Inclusion of Recovery Module in the README.
• Using the latest version of checkout (v4) for GitHub CI.

[coveralls]

Pull Request Test Coverage Report for Build 10037379863

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 10008091065:	0.0%
Covered Lines:	51
Relevant Lines:	51

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💛 - Coveralls