docs: update supported TS versions to include 4.1

[trivikr]

The support for TS 4.1 features was added in #2748

SUPPORTED_TYPESCRIPT_VERSIONS in parser:

typescript-eslint/packages/typescript-estree/src/parser.ts

Line 23 in a8227a6

const SUPPORTED_TYPESCRIPT_VERSIONS = '>=3.3.1 <4.2.0';

[typescript-eslint]

Thanks for the PR, @trivikr!

typescript-eslint is a 100% community driven project, and we are incredibly grateful that you are contributing to that community.

The core maintainers work on this in their personal time, so please understand that it may not be possible for them to review your work immediately.

Thanks again!

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[bradzacher]

thanks!