Documentation - Updated the ABI link

[connoraleks]

The application binary interface link used to point to https://github.com/ethereum/wiki/wiki/Ethereum-Contract-ABI when it should point to https://docs.soliditylang.org/en/develop/abi-spec.html

Description

Please include a summary of the changes and be sure to follow our Contribution Guidelines.

Type of change

• [ X] Bug fix (non-breaking change which fixes an issue)

Checklist:

• [X ] I have selected the correct base branch.
• [X ] I have performed a self-review of my own code.
• [ X] I have commented my code, particularly in hard-to-understand areas.
• [ X] I have made corresponding changes to the documentation.
• [ X] My changes generate no new warnings.
• [ X] Any dependent changes have been merged and published in downstream modules.
• [ X] I ran npm run dtslint with success and extended the tests and types if necessary.
• [ X] I ran npm run test:unit with success.
• [ X] I ran npm run test:cov and my test cases cover all the lines and branches of the added code.
• [ X] I ran npm run build and tested dist/web3.min.js in a browser.
• [X ] I have tested my code on the live network.
• [X ] I have checked the Deploy Preview and it looks correct.
• [ X] I have updated the CHANGELOG.md file in the root folder.