Update no-floating-promises lint rule docs page (vercel#36913)

Small docs fix. We've got a snazzy new website at typescript-eslint.io. Eventually the .md docs pages will serve just as partial docs sources, not the right URL to visit.

docs/api-reference/next/router.md

@@ -466,7 +466,7 @@ export default function MyApp({ Component, pageProps }) {
 
 ## Potential ESLint errors
 
-Certain methods accessible on the `router` object return a Promise. If you have the ESLint rule, [no-floating-promises](https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/no-floating-promises.md) enabled, consider disabling it either globally, or for the affected line.
+Certain methods accessible on the `router` object return a Promise. If you have the ESLint rule, [no-floating-promises](https://typescript-eslint.io/rules/no-floating-promises) enabled, consider disabling it either globally, or for the affected line.
 
 If your application needs this rule, you should either `void` the promise – or use an `async` function, `await` the Promise, then void the function call. **This is not applicable when the method is called from inside an `onClick` handler**.