`[_]::windows` needs better examples to avoid confusion

[JohnTheCoolingFan]

Location

https://doc.rust-lang.org/std/primitive.slice.html#method.windows

Summary

The documentation only shows an example with windows of size 2 and an example with windows of size 3, but the resulting slice is mutated and it woudl be hard to understand what exactly windows returns. For example, my previous assumption was that there was an overlap of only one element and not size - 1. An example with window size larger than 2 would help avoid this confusion.

[gurry]

@rustbot claim