Added text

Author: AtibQur

sites/cheerpx/src/content/docs/12-reference/CheerpX.OverlayDevice/create.md

@@ -1,6 +1,6 @@
 ---
 title: create
-description: Virtual filesystems and how to use them
+description: Create a writable persistent overlay device on top of another block device.
 ---
 
 ```ts
@@ -16,3 +16,39 @@ namespace CheerpX {
 - **baseDevice (`Device`)** - The underlying device (e.g., `HttpBytesDevice`, `IDBDevice`) that serves as the base layer for the filesystem.
 
 - **overlayDevice (`Device`)** - The writable layer that will overlay the base device, enabling persistent changes.
+
+## Returns
+
+`CheerpX.OverlayDevice.create` returns a [Promise] that resolves to an instance of the `OverlayDevice`. The `OverlayDevice` allows you to overlay a writable layer on top of the base device, enabling persistent changes while still accessing the base data.
+
+## Example
+
+Create an `OverlayDevice` instance to combine a `HttpBytesDevice` for streaming data from an HTTP source and an `IDBDevice` for caching and persistent local storage.
+
+```ts {8, 12}
+// Create a read-only HttpBytesDevice for streaming disk blocks via HTTP
+const httpDevice = await CheerpX.HttpBytesDevice.create("/cheerpXImage.ext2");
+
+// Create an IDBDevice for local persistent storage
+const idbDevice = await CheerpX.IDBDevice.create("block_idbDevice");
+
+// Create an OverlayDevice to combine the two devices
+const overlayDevice = await CheerpX.OverlayDevice.create(httpDevice, idbDevice);
+
+// Mount the overlay device in the CheerpX environment as an ext2 filesystem
+const cx = await CheerpX.Linux.create({
+  mounts: [{ type: "ext2", path: "/", dev: overlayDevice }],
+});
+```
+In this example, the `OverlayDevice` provides a writable layer on top of the `HttpBytesDevice` (which serves as a read-only block device for streaming), allowing changes to be stored locally via the `IDBDevice`.
+
+<!-- Add links when rest of the references are added -->
+<!-- ## Related sources
+
+- [Cheerp.HttpBytesDevice.create]()
+- [Cheerp.IDBDevice.create]()
+- [Cheerp.Linux.create]() -->
+
+For more information, please check out the [Files and File system guide](/docs/guides/File-System-support). This guide provides more details on how to work with files and directories in CheerpX.
+
+[Promise]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise