Fix XML comment on regex split enumerator (dotnet#111572)

Author: stephentoub

src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/Regex.EnumerateSplits.cs

@@ -267,9 +267,8 @@ public bool MoveNext()
             }
 
             /// <summary>
-            /// Gets the <see cref="ValueMatch"/> element at the current position of the enumerator.
+            /// Gets a <see cref="Range"/> for the split at the current position of the enumerator.
             /// </summary>
-            /// <exception cref="InvalidOperationException">Enumeration has either not started or has already finished.</exception>
             public readonly Range Current => _currentSplit;
         }
     }