Used for rendering the week number cell content in the month view of the Calendar. To define the month week number cell template,
nest an <ng-template> tag with the kendoCalendarWeekNumberCellTemplate directive inside the component tag. The template
context is set to the current component. To get a reference to the current date, use the let-date directive. To provide more
details about the current week number cell, get a reference to the current cellContext by using the let-cellContext directive.

For more examples, refer to the article on templates.

selector: 'my-app',
styles: ['.custom { color: red; }'],
template: `
 <kendo-calendar [weekNumber]="true">
   <ng-template kendoCalendarWeekNumberCellTemplate let-context="cellContext">
     <span class="custom">{{context.formattedValue}}</span>
class AppComponent { }