feat: add declaration file

[zanminkian]

No description provided.

[lydell]

I believe this would be the correct TypeScript declaration:

export = {
  rules: Record<string, 0 | "off">
}

[zanminkian]

I copied from @types/eslint-config-prettier. Maybe you are right.

[JounQin]

So if there is alreay @types/eslint-config-prettier, what the benefit to maintain it here?

[zanminkian]

@JounQin Therea are many eslint config packages published to npm. eslint-config-prettier builtin support declaration file will be convenient for other packages so that they don't neeed to install both eslint-config-prettier and @types/eslint-config-prettier