Fix the curl command for deleting files (DELETE instead of PUT)

doc/api/repository_files.md

@@ -113,7 +113,7 @@ DELETE /projects/:id/repository/files
 ```
 
 ```bash
-curl --request PUT --header 'PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK' 'https://gitlab.example.com/api/v3/projects/13083/repository/files?file_path=app/project.rb&branch_name=master&author_email=author%40example.com&author_name=Firstname%20Lastname&commit_message=delete%20file'
+curl --request DELETE --header 'PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK' 'https://gitlab.example.com/api/v3/projects/13083/repository/files?file_path=app/project.rb&branch_name=master&author_email=author%40example.com&author_name=Firstname%20Lastname&commit_message=delete%20file'
 ```
 
 Example response: