chore: remove dead links

README.md

@@ -66,7 +66,6 @@
 - [Cheatsheet](https://docs.soliditylang.org/en/latest/cheatsheet.html) - Cheatsheet from the official docs.
 - [Ethereum Wiki](https://github.com/ethereum/wiki/wiki) - The Ethereum Wiki.
 - [Ethereum Stackexchange](https://ethereum.stackexchange.com/) - Ethereum's Stackexchange board.
-- [Gitter](https://gitter.im/ethereum/solidity/) - Gitter channel.
 - [ethereum/solidity](https://github.com/ethereum/solidity/) - Source code.
 - [ethereum/solc-bin](https://github.com/ethereum/solc-bin) - Current and historical builds of the compiler.
 - [ethereum/solidity-examples](https://github.com/ethereum/solidity-examples) - Loose collection of example code.
@@ -97,7 +96,6 @@
 #### Articles
 
 - [Best Practices for Smart Contract Development (yos.io, Yos Riady, 2019)](https://yos.io/2019/11/10/smart-contract-development-best-practices/) - Developer handbook for smart contract developers.
-- [Clean Contracts (wslyvh.com, Wesley van Heije, 2020)](https://www.wslyvh.com/clean-contracts/) - Developer guide to writing clean smart contract code.
 - [The Complete Guide to Full Stack Ethereum Development (dev.to, Nader Dabit, 2021)](https://dev.to/dabit3/the-complete-guide-to-full-stack-ethereum-development-3j13) - Building Full Stack dApps with React, Ethers.js, Solidity, and Hardhat.
 - [How to create an ERC20 Token and a Solidity Vendor Contract (medium.com, Emanuele Ricci, 2021)](https://stermi.medium.com/how-to-create-an-erc20-token-and-a-solidity-vendor-contract-to-sell-buy-your-own-token-8882808dd905) - Create your own ERC20 Token and a Token Vendor Contract that will handle the sell/buy process.
 - [soliditydeveloper.com/blog](https://soliditydeveloper.com/blog) - Concepts, guides, design patterns and more.