Remove reference to golangci.com in README

[evalexpr]

This project is shutting down on the 15th April. See the blog below:
https://medium.com/golangci/golangci-com-is-closing-d1fc1bd30e0e

[CLAassistant]

All committers have signed the CLA.

[lopezator]

Thank you for this, we ❤️ doc contributions.

Apart from the changes proposed here there a more mentions in the README like the golangci.com configuration, for example.

This possibly also will need some change changes.

@jirfag do you prefer to do all at once, or are you ok with merging this and continue the remaining needed changes in future PRs?

[evalexpr]

I’m happy to make further changes if we want to remove everything in one PR. I’ll grep for the obvious stuff tomorrow and see if it’s easily removable.

[ernado]

Now we have a https://github.com/golangci/golangci-lint-action which is doing pretty similar what golangci did.

Probably we can promote this method as alternative.

[jirfag]

thank you,
I'm ok to remove it iteratively. In 1-2 weeks I would like to promote our GitHub action in README.