add Rust Iterator overview

[Aloso]

This is a learning resource, so I wasn't sure if Miscellaneous is the best category for this 🤷🏻

https://iterators.aloso.foo/

[mariannegoldin]

Hello, thank you very much for the submission.
This page, while informative, appears to duplicate some of of the official documentation in the Rust std library docs on Iterator and it is not clear on how interpret the implementation categories it provides. A blog or writeup introducing the tool, how it was created and how it should be used would be helpful. Please feel free to submit an update for issue 618; however, we cannot accept the submission for issue 617.