docs: clarify HasPrevious documentation in PolylineEncodingOptions

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Co-authored-by: petesramek <2333452+petesramek@users.noreply.github.com>

Author: Copilot

src/PolylineAlgorithm/PolylineEncodingOptions.cs

@@ -39,8 +39,9 @@ public PolylineEncodingOptions(TCoordinate previous) {
 
     /// <summary>
     /// Gets a value indicating whether a previous coordinate has been supplied to seed the delta
-    /// baseline. When <see langword="false"/> the formatter's built-in baseline (or zero) is used,
-    /// which is equivalent to the existing default behaviour.
+    /// baseline. When <see langword="false"/> the formatter's built-in baseline is used as the
+    /// starting point (which defaults to zero when no baseline has been configured), equivalent to
+    /// the existing default behaviour.
     /// </summary>
     public bool HasPrevious { get; }