chore: include CORS related config in the readme

README.md

@@ -42,6 +42,25 @@ uppy.addPreProcessor(() => {
 })
 ```
 
+Configure the CORS of your S3 or S3-compatible solution. It needs to allow GET and PUT requests from your domain and expose some unsafe HTTP headers to Uppy. Example:
+
+```json
+[
+ {
+ "AllowedOrigins": ["https://my-app.com"],
+ "AllowedMethods": ["GET", "PUT"],
+ "MaxAgeSeconds": 3000,
+ "AllowedHeaders": [
+ "Authorization",
+ "x-amz-date",
+ "x-amz-content-sha256",
+ "content-type"
+ ],
+ "ExposeHeaders": ["ETag", "Location"]
+ }
+]
+```
+
 ## Defaults
 
 The expiration times for the signe links is `15 minutes`.