* Add advanced download example
* Rename to task fields and variables
* Cargo fmt advanced_download/src/download.rs
* Add progress bar for advanced download example
* Merge two download examples to single one
* Apply great review suggestions
* Change to url::Url instead of plain String
* Simplify `download_progress` example
* Update `README` of `download_progress` example
Co-authored-by: Héctor Ramón Jiménez <hector0193@gmail.com>