The Creating .d.ts Files from .js files page's introduction reads:

With TypeScript 3.7, TypeScript added support for generating .d.ts files from JavaScript using JSDoc syntax.

This set up means you can own the editor experience of TypeScript-powered editors without porting your project to TypeScript, or having to maintain .d.ts files in your codebase. TypeScript supports most JSDoc tags, you can find the reference here.

The second link's target anchor does not exist anymore, so the link is confusing. The target page now contains the in-jsdoc-references anchor, but looking at the page quickly, it seems like what the link should really point to is the JSDoc Reference page.