Update README.md

Author: jesusbotella

README.md

@@ -1,2 +1,49 @@
-# mapboxgl-draw-rectangle-drag
-A Mapbox GL Draw plugin to create a rectangle via click & drag
+# Mapbox GL Draw Rectangle Drag
+A Mapbox GL Draw plugin to create a rectangle via click & drag.
+
+Based on [`thegisdev/mapbox-gl-draw-rectangle-mode`](https://github.com/thegisdev/mapbox-gl-draw-rectangle-mode) plugin code.
+
+How to install
+-----
+You can install this plugin either using npm or JSDeliver.
+
+### Using npm
+We deliver ESM compatible code through our npm module, so that you can import it in your project and compile it without issues.
+```
+npm i mapboxgl-draw-rectangle-drag --save
+```
+The module exports a default binding to the module, so you can import it like:
+```
+import mapboxGLDrawRectangleDrag from 'mapboxgl-draw-rectangle-drag';
+```
+
+### Using JSDeliver
+We have a script-compatible version of the plugin as well, ready to be imported in your HTML code using a `<script>` tag.
+```
+<script src="" />
+```
+
+A variable named `mapboxGLDrawRectangleDrag` is defined within the global scope to be included in your Mapbox GL Draw modes.
+
+Add mode to Mapbox GL Draw
+----
+Once the module/script is imported, you need to include the new mode within Mapbox GL's predefined modes.
+
+To do so, you need to include `modes` property in your Mapbox GL Draw configuration options.
+```js
+var MapboxGLDraw = new MapboxDraw({
+  modes: {
+    ...MapboxDraw.modes,
+    'draw_rectangle_drag': mapboxGLDrawRectangleDrag
+  }
+});
+```
+
+How to enable rectangle drag mode
+---
+To enable the rectangle drag mode, you need to execute [`changeMode`](https://github.com/mapbox/mapbox-gl-draw/blob/master/docs/API.md#changemodemode-string-options-object-draw) method on your Mapbox GL Draw instance.
+```
+drawInstance.changeMode('draw_rectangle_drag');
+```
+
+Unfortunately, custom modes cannot add custom controls to Mapbox GL Draw plugins. So, if you want to have a custom button to enable the control you need to create one by yourself. You can take some ideas from [this CodePen](https://codepen.io/roblabs/pen/zJjPzX)