docs(readme): add formats table, aspect-ratio note, example, related link

image-resizer/README.md

@@ -1,6 +1,6 @@
 # image-resizer
 
-Lightweight image resizing CLI written in Go.
+Lightweight image batch-resizer written in Go — scales images to a percentage of their original size while preserving aspect ratio.
 
 ## Build
 
@@ -10,10 +10,48 @@ go build -o image-resizer
 
 ## Usage
 
+Edit the `main()` function in `main.go` to set your source folder and scale percentage, then run:
+
 ```bash
-./image-resizer <input> <output> <width> <height>
+go run main.go
 ```
 
+Example — resize all images in a folder to 50%:
+
+```go
+folderPath   := "/path/to/images"
+scalePercent := 50    // 50% of original dimensions
+overwrite    := true  // overwrite originals; false saves to output folder
+```
+
+Output:
+```
+Image Resizer - Scaling to 50%
+Source folder: /path/to/images
+Mode: Overwriting original images
+--------------------------------------------------
+Resized: banner.png -> banner.png
+Resized: icon.jpg -> icon.jpg
+--------------------------------------------------
+Done!
+```
+
+## Supported formats
+
+| Input | Output |
+|-------|--------|
+| JPEG / JPG | JPEG (quality 95) |
+| PNG | PNG |
+| GIF | JPEG (quality 95) |
+| BMP | BMP |
+| TIFF / TIF | TIFF |
+
+Aspect ratio is always preserved — the scale percentage applies uniformly to both width and height.
+
+## Related
+
+- [webp-converter](https://github.com/tiennm99/webp-converter) — converts WebP images to PNG/JPG (same domain, different operation).
+
 ## License
 
-Apache-2.0
+Apache-2.0 — see [LICENSE](LICENSE).