DOC: Trivial typo fix in user_guide/window (#40666)
Trivial string change: `min_periods` corrected from `min_peridos`

Fixes Issue #40666 
thanks @mdengler 

for future reference, if you fill in the PR template like

```
- [x] closed #40666
- [ ] ...
```

then the issue will automatically be closed when the PR is merged > for future reference, if you fill in the PR template like
> 
> ```
> - [x] closed #40666
> - [ ] ...
> ```
> 
> then the issue will automatically be closed when the PR is merged

Thanks -- will do.