DataValidation wiki 3 years out of date.

## Read and complete the full issue template

Do not randomly delete sections. They are here for a reason.

**Do you want to request a *feature* or report a *bug*?**
- [] Bug
- [ ] Feature
- [X] Question

**Did you test against the latest CI build?**
- [X] Yes
- [ ] No

If you answered `No`, please test with [the latest development build](https://ci.appveyor.com/project/ClosedXML/ClosedXML/branch/develop/artifacts) first.

**Version of ClosedXML**

0.102.2

**What is the current behavior?**

Documentation at https://github.com/ClosedXML/ClosedXML/wiki/Data-Validation refers to
```cs
ws.Cell(1, 1).DataValidation.Decimal.Between(1, 5);
```
The DataValidation field was removed in 2021 in this change https://github.com/ClosedXML/ClosedXML/commit/478706c55db2cc39bfa1d01e80550d34ff1a1660

**What is the expected behavior or new feature?**

Documentation is accurate to use CreateDataValidation() (I think?)

**Is this a regression from the previous version?**

This would be a regression for all versions since and including 0.96.0

## Reproducibility

Code as written in wiki fails to compile:

**Code to reproduce problem:**
```c#
public void Main()
{
var wb = new XLWorkbook();
var ws = wb.Worksheets.Add("Data Validation");
ws.Cell(1, 1).DataValidation.Decimal.Between(1, 5);
}
```

Open the ClosedXML wiki page at /wiki/Data-Validation and review the API change linked in the issue. Check the current data-validation entry point and update the obsolete C# example so it compiles with ClosedXML 0.102.2 or later. Done means the page no longer references the removed DataValidation field and shows the current usage.

Written by the indexing model from the issue text.