Fix typo in DataType description

Author: bjarnef

16/umbraco-forms/developer/extending/adding-a-fieldtype.md

@@ -60,7 +60,7 @@ In the constructor or via overridden properties, we can specify details of the f
 * `Name` - the name of the field presented in the backoffice.
 * `Description` - the description of the field presented in the backoffice.
 * `Icon` - the icon of the field presented in the backoffice form builder user interface.
-* `DataType` - specifies the type of data stored by the field. Options are `String`, `LongString`, `Integer`, `DataTime` or `Bit` (boolean).
+* `DataType` - specifies the type of data stored by the field. Options are `String`, `LongString`, `Integer`, `DateTime` or `Bit` (boolean).
 * `SupportsMandatory` - indicates whether mandatory validation can be used with the field (defaults to `true`).
 * `MandatoryByDefault` - indicates whether the field will be mandatory by default when added to a form (defaults to `false`).
 * `SupportsRegex` - indicates whether pattern-based validation using regular expressions can be used with the field (defaults to `false`).