Add Yang-Zhang Volatility (YZV) Indicator Implementation

- Introduced YZV class for calculating Yang-Zhang Volatility, a comprehensive volatility measure that incorporates overnight, open-to-close, and high-low components.
- Implemented calculation methods, including batch processing for TBarSeries and spans.
- Added documentation for YZV, detailing its mathematical foundation, performance profile, and trading applications.
- Updated volume index documentation to reflect changes in file paths.
- Refactored VWMA calculation method to use a more generic source parameter instead of price.

lib/volatility/vr/Vr.Quantower.cs

@@ -0,0 +1,49 @@
+using System.Drawing;
+using System.Runtime.CompilerServices;
+using TradingPlatform.BusinessLayer;
+
+namespace QuanTAlib;
+
+[SkipLocalsInit]
+public sealed class VrIndicator : Indicator, IWatchlistIndicator
+{
+    [InputParameter("Period", sortIndex: 1, 1, 200, 1, 0)]
+    public int Period { get; set; } = 14;
+
+    [InputParameter("Show cold values", sortIndex: 21)]
+    public bool ShowColdValues { get; set; } = true;
+
+    private Vr _vr = null!;
+    private readonly LineSeries _series;
+
+    public static int MinHistoryDepths => 0;
+    int IWatchlistIndicator.MinHistoryDepths => MinHistoryDepths;
+
+    public override string ShortName => $"VR({Period})";
+    public override string SourceCodeLink => "https://github.com/mihakralj/QuanTAlib/blob/main/lib/volatility/vr/Vr.Quantower.cs";
+
+    public VrIndicator()
+    {
+        OnBackGround = true;
+        SeparateWindow = true;
+        Name = "VR - Volatility Ratio";
+        Description = "Volatility Ratio measures current True Range relative to Average True Range, identifying potential breakout conditions when the ratio exceeds threshold values";
+
+        _series = new LineSeries(name: "VR", color: IndicatorExtensions.Volatility, width: 2, style: LineStyle.Solid);
+        AddLineSeries(_series);
+    }
+
+    protected override void OnInit()
+    {
+        _vr = new Vr(Period);
+        base.OnInit();
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    protected override void OnUpdate(UpdateArgs args)
+    {
+        TBar bar = this.GetInputBar(args);
+        TValue result = _vr.Update(bar, isNew: args.IsNewBar());
+        _series.SetValue(result.Value, _vr.IsHot, ShowColdValues);
+    }
+}