Add watermark property comments
Add watermark property comments

SuperJMN/Avalonia,SuperJMN/Avalonia,SuperJMN/Avalonia,SuperJMN/Avalonia,SuperJMN/Avalonia,grokys/Perspex,AvaloniaUI/Avalonia,AvaloniaUI/Avalonia,AvaloniaUI/Avalonia,AvaloniaUI/Avalonia,AvaloniaUI/Avalonia,AvaloniaUI/Avalonia,AvaloniaUI/Avalonia,SuperJMN/Avalonia,SuperJMN/Avalonia,grokys/Perspex