C#: Address other CoPilot review comments.

Author: michaelnebel

csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/ElementAccess.cs

@@ -103,9 +103,10 @@ private Expression CreateFromRangeEndpoint(TextWriter trapFile, IPropertySymbol
 
         /// <summary>
         /// Determines whether the given method is a slice method, which is defined as a method with
-        /// the name "Slice" or "SubString" and two parameters.
-        /// </summary> <param name="method">The method symbol to check.</param>
-        /// <returns>True if the method is a slice method, false otherwise.</returns>
+        /// the name "Slice" or "Substring" and two parameters.
+        /// </summary>
+        /// <param name="method">The method symbol to check.</param>
+        /// <returns>True if the method is a slice method; false otherwise.</returns>
         private bool IsSliceWithRange(IMethodSymbol method, [NotNullWhen(true)] out IPropertySymbol? lengthPropertySymbol, [NotNullWhen(true)] out RangeExpressionSyntax? range)
         {
             range = null;

csharp/ql/lib/change-notes/2026-05-21-spanaccess-range.md

@@ -1,4 +1,4 @@
 ---
 category: minorAnalysis
 ---
-* Improved extraction of span range-access expressions (for example, `a[0..3]`). These expressions are now extracted as span `Slice` calls.
+* Improved extraction of range-access expressions on spans and strings (for example, `a[0..3]`). These expressions are now extracted as `Slice` (span) or `Substring` (string) calls.