[Feature Request] xref link doesn't work as an include link

**Is your feature request related to a problem? Please describe.**
When attempting to use an xref in an [!INCLUDE] directive it doesn't work.

For example:

Doesn't work
```md
[!INCLUDE [Platforms](xref:GettingStarted.UsingWizard.Platforms)]
```

Works:

```md
[!INCLUDE [Platforms](using-wizard/platforms.md)]
```

**Describe the solution you'd like**
Enable using xref links in include links.

**Describe alternatives you've considered**
Using url instead, which is not very productive.