docs: Update note about ECMAScript support (#17991)

* docs: Update note about default ECMAScript version

* remove mention about environments (legacy feature)

* Apply suggestions from code review

Co-authored-by: Nicholas C. Zakas <nicholas@humanwhocodes.com>

* Clarify supported year range

* Update README.md

Co-authored-by: Francesco Trotta <github@fasttime.org>

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Co-authored-by: Nicholas C. Zakas <nicholas@humanwhocodes.com>

README.md

@@ -117,7 +117,7 @@ Yes, ESLint natively supports parsing JSX syntax (this must be enabled in [confi
 
 ### What ECMAScript versions does ESLint support?
 
-ESLint has full support for ECMAScript 3, 5 (default), 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, and 2023. You can set your desired ECMAScript syntax (and other settings, like global variables or your target environments) through [configuration](https://eslint.org/docs/latest/use/configure).
+ESLint has full support for ECMAScript 3, 5, and every year from 2015 up until the most recent stage 4 specification (the default). You can set your desired ECMAScript syntax and other settings (like global variables) through [configuration](https://eslint.org/docs/latest/use/configure).
 
 ### What about experimental features?