Add Supercool to the "Tools" section

[dbmikus]

Add Supercool to the "Tools" section. It is relayer and account abstraction infra to automate smart contract interactions and give your users better UX when executing transactions.

Disclaimer: I am a co-founder of Supercool, but wanted to share. We're developers and built the relayer and transaction infra we wish we had when working on other projects.

Checklist

• The URL is not already present in the list (check with CTRL/CMD+F in the raw markdown file).
• Each description starts with an uppercase character and ends with a period.
  Example: solc-js - JavaScript bindings for the compiler.
• Drop all A / An prefixes at the start of the description.
• Avoid using the word Solidity in the description.

[dbmikus]

Would it be better to link to our homepage or to our docs?