Documentation for Control.DeviceDPI needs link to info about DPI

### Type of issue

Missing information

### Description

This should be relatively obvious, that anyone looking at this page of info (Control.DeviceDPI) might want to find more information about DPI values, what they mean, what their expected range of values might be, etc. But there is no link here to further information. In fact, the reader is left wondering even where to look for it.

### Page URL

https://learn.microsoft.com/en-us/dotnet/api/system.windows.forms.control.devicedpi?view=windowsdesktop-9.0#system-windows-forms-control-devicedpi

### Content source URL

https://github.com/dotnet/dotnet-api-docs/blob/main/xml/System.Windows.Forms/Control.xml

### Document Version Independent Id

0fb53ec8-3f96-e407-8c9d-79ae0e67a15f

### Article author

@dotnet-bot