Add configuration example to README.md

README.md

@@ -5,20 +5,34 @@ Easy-to-use library to create image thumbnails from images existing on some (clo
 Currently implemented is a connection to Google Cloud Storage, but it can be easily extended to other providers.
 
 # How to use
+Configure what thumbnails you would like to have:
+```yaml
+thumbs:
+  - name: standard      # this name will be added to the thumbnail with an underscore (_)
+    quality: 80         # PNG ignores this variable as it is always lossless
+    size: [ 640, 480 ]  # Target size of the thumbnail. May not always be exact.
+    mode: fit           # available are: 'fit' and 'crop'
 
- ```rust
+  - name: mini
+    quality: 80
+    size: [ 40, 40 ]
+    mode: crop
+```
+
+Then use it in your code 
+```rust
 #[tokio::main]
 async fn main() {
     let thumbs = image_thumbs::ImageThumbs::new("examples/image_thumbs")
         .await
         .unwrap();
     thumbs
-        .create_thumbs("penguin.jpg", "/thumbs", false)
+        .create_thumbs("penguin.jpg", "/thumbs", false)  // do not override existing images
         .await
         .unwrap();
     thumbs
-        .create_thumbs("penguin.png", "/thumbs", false)
+        .create_thumbs("penguin.png", "/thumbs", true)  // do override existing images
         .await
         .unwrap();
 }
- ```
+```