Add Slippy to the list of Solidity tools

[fvictorio]

Added Slippy, a Solidity linter I'm working on, to the list of Solidity tools.

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[mehtavishwa30]

Thanks for your contributions to Solidity resources page, @fvictorio. We curate all the resources here carefully based on maturity, usage, and interest around the tooling in the Solidity community and ecosystem.

Since Slippy is a relatively new tool, we would like to take some time to observe how it grows and add it later based on feedback from our surveys. I will be closing this PR on the above grounds for now.

[fvictorio]

Hi @mehtavishwa30, it's been a couple of months now. Slippy has been adopted by a few serious projects and popular templates and I'm very actively maintaining it. Would you be open to including it now?

Btw, this list also includes ethlint, which hasn't had a new version in six years (!), doesn't work with new versions of Solidity, and basically no one uses. Maybe Slippy doesn't have the level of adoption that it needs to be included, but in that case I think ethlint should be dropped from the list, because it's clearly a worse tool to recommend to users.

[clonker]

Hey @fvictorio, we revisited the topic internally and will merge your suggestion. Although it seems like our spellchecker is tripping up over Slippy (slipping, so to say...). Mind adding the Slippy line to codespell_whitelist.txt? That should fix it.