update docs

Author: zloirock

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## Changelog
 ##### Unreleased
+- [`Array` grouping proposal](https://github.com/tc39/proposal-array-grouping):
+  - Moved to the stage 2
+  - Added `Array.prototype.groupByMap` method
+  - Removed `@@species` support
 - Added [change `Array` by copy stage 2 proposal](https://github.com/tc39/proposal-change-array-by-copy):
   - `Array.prototype.toReversed`
   - `Array.prototype.toSorted`

README.md

@@ -101,6 +101,7 @@ Promise.resolve(32).then(x => console.log(x)); // => 32
       - [`Iterator` helpers](#iterator-helpers)
       - [New `Set` methods](#new-set-methods)
       - [`Map.prototype.emplace`](#mapprototypeemplace)
+      - [`Array` grouping](#array-grouping)
       - [Change `Array` by copy](#change-array-by-copy)
       - [`Array.isTemplateObject`](#arrayistemplateobject)
       - [`Symbol.{ asyncDispose, dispose }` for `using` statement](#symbol-asyncdispose-dispose--for-using-statement)
@@ -112,7 +113,6 @@ Promise.resolve(32).then(x => console.log(x)); // => 32
       - [`compositeKey` and `compositeSymbol`](#compositekey-and-compositesymbol)
       - [`Array.fromAsync`](#arrayfromasync)
       - [`Array` filtering](#array-filtering)
-      - [`Array` grouping](#array-grouping)
       - [`Array` deduplication](#array-deduplication)
       - [Getting last item from `Array`](#getting-last-item-from-array)
       - [`Number.range`](#numberrange)
@@ -2353,7 +2353,7 @@ console.log(compositeSymbol(1, a, 2, b) === compositeSymbol(1, a, 2, b)); // =>
 console.log(compositeSymbol(a, a) === compositeSymbol(a, a)); // => true
 ```
 ##### [`Array.fromAsync`](https://github.com/tc39/proposal-array-from-async)[⬆](#index)
-Modules [`esnext.array.from-async`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/esnext.array.from-async.js) and [`esnext.typed-array.from-async`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/esnext.typed-array.from-async.js)
+Modules [`esnext.array.from-async`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/esnext.array.from-async.js).
 ```js
 class Array {
   static fromAsync(asyncItems: AsyncIterable | Iterable | ArrayLike, mapfn?: (value: any, index: number) => any, thisArg?: any): Array;
@@ -2390,7 +2390,7 @@ core-js/features/typed-array/filter-reject
 [1, 2, 3, 4, 5].filterReject(it => it % 2); // => [2, 4]
 ````
 ##### [`Array` grouping](#https://github.com/tc39/proposal-array-grouping)[⬆](#index)
-Modules [`esnext.array.group-by`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/esnext.array.group-by.js).
+Modules [`esnext.array.group-by`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/esnext.array.group-by.js), [`esnext.array.group-by-map`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/esnext.array.group-by-map.js).
 ```js
 class Array {
   groupBy(callbackfn: (value: any, index: number, target: any) => key, thisArg?: any): { [key]: Array<mixed> };
@@ -2401,10 +2401,14 @@ class Array {
 ```
 core-js/proposals/array-grouping
 core-js(-pure)/features/array(/virtual)/group-by
+core-js(-pure)/features/array(/virtual)/group-by-map
 ```
-[*Examples*](t.ly/VggI):
+[*Examples*](t.ly/xEqc):
 ```js
 [1, 2, 3, 4, 5].groupBy(it => it % 2); // => { 1: [1, 3, 5], 0: [2, 4] }
+const map = [1, 2, 3, 4, 5].groupByMap(it => it % 2);
+map.get(1); // => [1, 3, 5]
+map.get(0); // => [2, 4]
 ````
 ##### [Array deduplication](https://github.com/tc39/proposal-array-unique)[⬆](#index)
 Modules [`esnext.array.unique-by`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/esnext.array.unique-by.js) and [`esnext.typed-array.unique-by`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/esnext.typed-array.unique-by.js)
@@ -3076,4 +3080,4 @@ console.log(getIteratorMethod({})); // undefined
 - ES `Proxy` can't be polyfilled, you can try to use [`proxy-polyfill`](https://github.com/GoogleChrome/proxy-polyfill) which provides a very little subset of features.
 - ES `String#normalize` is not a very useful feature, but this polyfill will be very large. If you need it, you can use [unorm](https://github.com/walling/unorm/).
 - ECMA-402 `Intl` is missed because of the size. You can use [those polyfills](https://formatjs.io/docs/polyfills).
-- `window.fetch` is not a cross-platform feature, in some environments, it makes no sense. For this reason, I don't think it should be in `core-js`. Looking at a large number of requests it *might be*  added in the future. Now you can use, for example, [this polyfill](https://github.com/github/fetch).
+- `window.fetch` is not a cross-platform feature, in some environments, it makes no sense. For this reason, I don't think it should be in `core-js`. Looking at a large number of requests it *might be*  added in the future. Now you can use, for example, [this polyfill](https://github.com/github/fetch).