docs(mf2/messageformat): Update README

Author: XM5jDcsHTyGJtQqlCi

mf2/messageformat/README.md

@@ -1,51 +1,63 @@
-# A Polyfill for Intl.MessageFormat
+# MessageFormat 2 for JavaScript
 
-This library provides a runtime for the [ECMA-402 Intl.MessageFormat proposal],
-which is built on top of the developing [Unicode MessageFormat 2.0 specification], "MF2".
+This library provides an implementation of the [ECMA-402 Intl.MessageFormat proposal],
+which is built on top of the [Unicode MessageFormat 2.0 specification] (MF2),
+developed by the [MessageFormat Working Group].
 
-[ecma-402 intl.messageformat proposal]: https://github.com/dminor/proposal-intl-messageformat/
-[unicode messageformat 2.0 specification]: https://github.com/unicode-org/message-format-wg
-
-> **NOTE**: This means that the v4 release of the `messageformat` package has
-> an entirely different API compared to its earlier major releases,
-> which were built on top of ICU MessageFormat, aka "MF1".
-> For that,
-> please see [`@messageformat/core`](https://www.npmjs.com/package/@messageformat/core) instead.
+The API provided by this library is current as of the [LDML 46.1] (December 2024)G
+version of the MF2 specification.
 
-## Usage
+[ecma-402 intl.messageformat proposal]: https://github.com/dminor/proposal-intl-messageformat/
+[unicode messageformat 2.0 specification]: https://unicode.org/reports/tr35/tr35-messageFormat.html
+[messageformat working group]: https://github.com/unicode-org/message-format-wg
+[LDML 46.1]: https://www.unicode.org/reports/tr35/tr35-74/tr35-messageFormat.html
 
 ```sh
 npm install --save-exact messageformat@next
 ```
 
 ```js
 import { MessageFormat } from 'messageformat';
-Intl.MessageFormat = MessageFormat;
+
+const msg = 'Today is {$today :datetime dateStyle=medium}';
+const mf = new MessageFormat('en', msg);
+
+mf.format({ today: new Date('2022-02-02') });
+// 'Today is Feb 2, 2022'
 ```
 
-In addition to supporting MF2 syntax,
-compilers and formatting function runtimes are also provided for
-ICU MessageFormat and Fluent messages:
+The library also provides a number of other tools and utilities for MF2, such as:
 
-- [@messageformat/icu-messageformat-1](https://www.npmjs.com/package/@messageformat/icu-messageformat-1)
-- [@messageformat/fluent](https://www.npmjs.com/package/@messageformat/fluent)
+- MF2 data model conversion tools
 
-## API
+  ```js
+  import { parseMessage, stringifyMessage } from 'messageformat';
+  ```
 
-The API provided by this Intl.MessageFormat polyfill is current as of
-[2022-07-13](https://github.com/tc39/proposal-intl-messageformat/blob/72eefa5/README.md).
-The static `MessageFormat.parseResource()` method is not yet provided,
-as the message resource syntax is still under development.
+- MF2 data model validation and transformation tools
 
-```js
-const locale = 'en-US';
-const msg = '{Today is {$today :datetime dateStyle=medium}}';
+  ```js
+  import { validate, visit } from 'messageformat';
+  ```
 
-const mf = new Intl.MessageFormat(msg, locale);
+- Concreate Syntax Tree (CST) tools for MF2
+  ```js
+  import { parseCST, messageFromCST, stringifyCST } from 'messageformat';
+  ```
 
-mf.format({ today: new Date('2022-02-02') });
-// 'Today is Feb 2, 2022'
-```
+In addition to supporting MF2 syntax,
+compilers and formatting function runtimes are also provided for
+ICU MessageFormat and Fluent messages:
+
+- [@messageformat/icu-messageformat-1](https://www.npmjs.com/package/@messageformat/icu-messageformat-1)
+- [@messageformat/fluent](https://www.npmjs.com/package/@messageformat/fluent)
 
 For more information on additional types and functions provided by this package,
 see the [API documentation site](https://messageformat.github.io/messageformat/api/).
+
+> [!IMPORTANT]
+> This means that the v4 release of the `messageformat` package has
+> an entirely different API compared to its earlier major releases,
+> which were built on top of ICU MessageFormat, aka "MF1".
+> For that,
+> please see [`@messageformat/core`](https://www.npmjs.com/package/@messageformat/core) instead.