updated readme

Author: ANKUR DWIVEDI

README.md

@@ -352,6 +352,29 @@ image_url = imagekit.url({
 https://ik.imagekit.io/your_imagekit_id/tr:h-300,w-400,l-image,i-ik_canvas,bg-FF0000,w-300,h-100,l-end/img/sample-video.mp4
 ```
 
+**5. Arithmetic expressions In transformations**
+
+ImageKit allows use of [arithmetic expressions](https://docs.imagekit.io/features/arithmetic-expressions-in-transformations) in certain dimension and position-related parameters, making media transformations more flexible and dynamic.
+
+For example:
+
+```ruby
+image_url = imagekit.url({
+    path: "/default-image.jpg",
+    url_endpoint: "https://ik.imagekit.io/your_imagekit_id/endpoint/",
+    transformation: [{
+        width: "iw_div_4",
+        height: "ih_div_2",
+        border: "cw_mul_0.05_yellow"
+    }]
+});
+```
+
+**Sample Result URL**
+```
+https://ik.imagekit.io/your_imagekit_id/default-image.jpg?tr=w-iw_div_4,h-ih_div_2,b-cw_mul_0.05_yellow
+```
+
 **List of transformations**
 
 The complete list of transformations supported and their usage in ImageKit can be found [here](https://docs.imagekit.io/features/image-transformations/resize-crop-and-other-transformations). The SDK gives a name to each transformation parameter, making the code simpler, making the code simpler, and readable.
@@ -364,10 +387,10 @@ If you want to generate transformations in your application and add them to the
 |-------------------------------|-------------------------|
 | height | h |
 | width | w |
-| aspectRatio | ar |
+| aspect_ratio | ar |
 | quality | q |
 | crop | c |
-| cropMode | cm |
+| crop_mode | cm |
 | x | x |
 | y | y |
 | focus | fo |
@@ -382,13 +405,15 @@ If you want to generate transformations in your application and add them to the
 | lossless | lo |
 | trim | t |
 | metadata | md |
-| colorProfile | cp |
-| defaultImage | di |
+| color_profile | cp |
+| default_image | di |
 | dpr | dpr |
-| effectSharpen | e-sharpen |
-| effectUSM | e-usm |
-| effectContrast | e-contrast |
-| effectGray | e-grayscale |
+| effect_sharpen | e-sharpen |
+| effect_usm | e-usm |
+| effect_contrast | e-contrast |
+| effect_gray | e-grayscale |
+| effect_shadow | e-shadow |
+| effect_gradient | e-gradient |
 | original | orig |
 | raw | `replaced by the parameter value` |