Add Rectangle examples with corner radius
Add Rectangle examples with corner radius

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