Add hint to the presign documentation how to upload a file (#1673)

* Add hint to the presign documentation how to upload a file

I was confused that I can not upload a file until I realized that the Request was explicitly "Get" and I had simply to switch it to "Put" to upload files via the presigned url.

* Update docs/features/presign.md

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Co-authored-by: Jérémy Derussé <[email protected]>

Author: thedomeffm

docs/features/presign.md

@@ -13,13 +13,20 @@ for a limited time.
 
 ```php
 use AsyncAws\S3\Input\GetObjectRequest;
+use AsyncAws\S3\Input\PutObjectRequest;
 use AsyncAws\S3\S3Client;
 
 $s3 = new S3Client();
+// To allow reading of a file use:
 $input = new GetObjectRequest([
     'Bucket' => 'my-bucket',
     'Key' => 'test',
 ]);
+// To allow uploading a file use:
+// $input = new PutObjectRequest([
+//     'Bucket' => 'my-bucket',
+//     'Key' => 'test',
+// ]);
 
 $url = $s3->presign($input, new \DateTimeImmutable('+60 min'));