docs: update README to include overlay options and configuration details

Author: manu4543

README.md

@@ -18,6 +18,10 @@ Lightweight JavaScript SDK for generating optimized URLs for images and videos,
 - [URL Generation](#url-generation)
   - [Basic URL Generation](#basic-url-generation)
   - [Advanced URL Generation Examples](#advanced-url-generation-examples)
+    - [Chained Transformations](#chained-transformations)
+    - [Overlays and Effects](#overlays-and-effects)
+    - [AI and Advanced Transformations](#ai-and-advanced-transformations)
+    - [Arithmetic Expressions in Transformations](#arithmetic-expressions-in-transformations)
   - [Supported Transformations](#supported-transformations)
   - [Handling Unsupported Transformations](#handling-unsupported-transformations)
 - [File Upload](#file-upload)
@@ -244,6 +248,18 @@ var solidColorOverlayURL = imagekit.url({
 });
 ```
 
+**Overlay Options**
+
+The following table details the overlay configuration options as defined in the SDK. These options are passed in the overlay object and directly map to URL parameters:
+
+| option   | Description                                                                                                                                                                                                                                                             | Example                                       |
+| -------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------- |
+| encoding | Specifies how the overlay input is encoded. The default is "auto", meaning the SDK automatically determines whether to use plain (`i-{input}`) or base64 (`ie-{base64_encoded_input}`) encoding based on the content. You can explicitly set it to "plain" or "base64". | `encoding: "plain"`                           |
+| position | Defines the overlay's placement relative to the parent asset. Accepts a JSON object with properties: `x` and `y` for coordinates (which can be arithmetic expressions) or a `focus` value such as "center", "top_left", etc.                                            | `position: { x: 10, y: 20, focus: "center" }` |
+| timing   | When the base asset is video, specifies when the overlay appears. It accepts a JSON object with values for `start`, `duration`, and `end`. If both `duration` and `end` are provided, `duration` is ignored.                                                            | `timing: { start: 5, duration: 10, end: 15 }` |
+
+These options provide developers with fine-grained control over overlay transformations, ensuring that the generated URL accurately reflects the desired overlay configuration.
+
 #### AI and Advanced Transformations
 *Background Removal:*
 ```js