Update README.md

Author: danielnixon

README.md

@@ -55,7 +55,7 @@ The first column ("Even Better 🚀") contains types that are more than just imm
 | | `ReadonlyWeakMap` | | | [`WeakMap`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap) |
 | [fp-ts's `Either`](https://gcanti.github.io/fp-ts/modules/Either.ts.html) | `ReadonlyError` (and friends) | | | [`Error` and friends](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects#error_objects) |
 | | `ReadonlyRegExp` | | | `RegExp` |
-| [fp-ts's `TaskEither`](https://gcanti.github.io/fp-ts/modules/TaskEither.ts.html), and eventually [Effect](https://www.effect.website/docs/what-is-effect) | `ReadonlyPromise` | `Promise` | | |
+| [fp-ts's `TaskEither`](https://gcanti.github.io/fp-ts/modules/TaskEither.ts.html), and eventually [Effect](https://github.com/Effect-TS/effect) | `ReadonlyPromise` | `Promise` | | |
 | | `DeepImmutable` | | | [`DeepReadonly` from ts-essentials](https://github.com/ts-essentials/ts-essentials/blob/master/lib/types.ts#L156-L181), which when used will produce a mix of `Mutable` and `ReadonlyDeep` types |
 * PRs welcome!