Cleanedup the CHANGELOG. Updated README.

CHANGELOG.md

+Changelog
+=========
+

README.md

+CKEditor 5 decoupled document build
+========================================
+
+[![Join the chat at https://gitter.im/ckeditor/ckeditor5](https://badges.gitter.im/ckeditor/ckeditor5.svg)](https://gitter.im/ckeditor/ckeditor5?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![npm version](https://badge.fury.io/js/%40ckeditor%2Fckeditor5-build-decoupled-document.svg)](https://www.npmjs.com/package/@ckeditor/ckeditor5-build-decoupled-document)
+[![Dependency Status](https://david-dm.org/ckeditor/ckeditor5-build-decoupled-document/status.svg)](https://david-dm.org/ckeditor/ckeditor5-build-decoupled-document)
+[![devDependency Status](https://david-dm.org/ckeditor/ckeditor5-build-decoupled-document/dev-status.svg)](https://david-dm.org/ckeditor/ckeditor5-build-decoupled-document?type=dev)
+
+The decoupled document build for CKEditor 5. Read more about the [decoupled document build](TODO) and see the [demo](TODO).
+
+## Documentation
+
+See:
+
+* [Installation](https://ckeditor5.github.io/docs/nightly/ckeditor5/latest/builds/guides/integration/installation.html) for how to install this package and what it contains.
+* [Basic API](https://ckeditor5.github.io/docs/nightly/ckeditor5/latest/builds/guides/integration/basic-api.html) for how to create an editor and interact with it.
+* [Configuration](https://ckeditor5.github.io/docs/nightly/ckeditor5/latest/builds/guides/integration/configuration.html) for how to configure the editor.
+* [Creating custom builds](https://ckeditor5.github.io/docs/nightly/ckeditor5/latest/builds/guides/development/custom-builds.html) for how to customize the build (configure and rebuild the editor bundle).
+
+## Quick start
+
+First, install the build from npm:
+
+```
+npm install --save @ckeditor/ckeditor5-build-decoupled-document
+```
+
+And use it in your website:
+
+```html
+<div id="editor">
+	<p>This is the editor content.</p>
+</div>
+<script src="./node_modules/@ckeditor/ckeditor5-build-decoupled-document/build/ckeditor.js"></script>
+<script>
+	ClassicEditor
+		.create( '<h2>Hello world!</h2>', {
+			toolbarContainer: '.toolbar-container',
+			editableContainer: '.editable-container'
+		} )
+		.then( editor => {
+			window.editor = editor;
+		} )
+		.catch( err => {
+			console.error( err.stack );
+		} );
+</script>
+```
+
+Or in your JavaScript application:
+
+```js
+import ClassicEditor from '@ckeditor/ckeditor5-build-decoupled-document';
+
+// Or using CommonJS verion:
+// const ClassicEditor = require( '@ckeditor/ckeditor5-build-decoupled-document' );
+
+ClassicEditor
+	.create( '<h2>Hello world!</h2>', {
+			toolbarContainer: '.toolbar-container',
+			editableContainer: '.editable-container'
+		} )
+	.then( editor => {
+		window.editor = editor;
+	} )
+	.catch( err => {
+		console.error( err.stack );
+	} );
+```
+
+**Note:** If you are planning to integrate CKEditor 5 deep into your application, it is actually more convenient and recommended to install and import the source modules directly (like it happens in `ckeditor.js`). Read more in the [Advanced setup guide](https://ckeditor5.github.io/docs/nightly/ckeditor5/latest/builds/guides/integration/advanced-setup.html).
+
+## License
+
+Licensed under the GPL, LGPL and MPL licenses, at your choice. For full details about the license, please check the `LICENSE.md` file.