Apply suggestions from code review

Author: Oxyjun

src/content/docs/r2/examples/aws/aws-sdk-rust.mdx

@@ -88,7 +88,7 @@ async fn main() -> Result<(), s3::Error> {
 }
 ```
 
-## Uploading Objects
+## Upload Objects
 
 To upload an object to R2:
 
@@ -117,7 +117,7 @@ async fn upload_object(
 }
 ```
 
-## Downloading Objects
+## Download Objects
 
 To download an object from R2: