Article for C# developer should also mention Span<T> and inline arrays

[laicasaane]

https://github.com/microsoft/RustTraining/blob/96d56128575a3f051c20fd4933610266b3432986/csharp-book/src/ch05-data-structures-and-collections.md#arrays-and-slices

The current article failed to mention the long-lived Span<T> and the recent advent of Inline Arrays thus doesn't provide a comprehensive translation between the recent C# and Rust on this specific topic.

[atulkhare4096]

@laicasaane My knowledge of C# is arguably rusty :). Do you have any good resources on the above? If you know the right changes off the top of your head, please feel free to submit a PR.