fix: Heikin-Ashi().ToQuotes() (#881)

Author: DaveSkender

docs/_indicators/HeikinAshi.md

@@ -53,10 +53,10 @@ IEnumerable<HeikinAshiResult>
 
 - [.Find(lookupDate)]({{site.baseurl}}/utilities#find-indicator-result-by-date)
 - [.RemoveWarmupPeriods(qty)]({{site.baseurl}}/utilities#remove-warmup-periods)
-- .ToQuotes() to convert to a `Quote` list.  Example:
+- .ToQuotes() to convert to a `Quote` collection.  Example:
 
   ```csharp
-  List<Quote> results = quotes.GetHeikinAshi().ToQuotes();
+  IEnumerable<Quote> results = quotes.GetHeikinAshi().ToQuotes();
   ```
 
 See [Utilities and Helpers]({{site.baseurl}}/utilities#utilities-for-indicator-results) for more information.

src/e-k/HeikinAshi/HeikinAshi.Utilities.cs

@@ -3,7 +3,7 @@ namespace Skender.Stock.Indicators;
 public static partial class Indicator
 {
     // convert results to quotes
-    internal static List<Quote> ToQuotes(
+    public static IEnumerable<Quote> ToQuotes(
     this IEnumerable<HeikinAshiResult> results)
       => results
         .Select(x => new Quote

tests/indicators/e-k/HeikinAshi/HeikinAshi.Tests.cs

@@ -37,7 +37,7 @@ public void UseAsQuotes()
     public void ToQuotes()
     {
         List<HeikinAshiResult> results = quotes.GetHeikinAshi().ToList();
-        List<Quote> haQuotes = results.ToQuotes();
+        List<Quote> haQuotes = results.ToQuotes().ToList();
 
         for (int i = 0; i < results.Count; i++)
         {