docs(abstractions): correct ReadEventsAsync remark — OpcUaClient now overrides

Code-review minor: the DIM remark said the OPC UA Client driver stays with the
default; it now overrides (forwards HistoryReadEvents upstream). Comment-only —
no contract/signature change. The session-capture-before-gate race the review
also noted is a pre-existing ExecuteHistoryReadAsync pattern (shared by
raw/processed/attime); ReadEventsAsync intentionally mirrors it — tracked as a
follow-up to fix all four history paths together.

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IHistoryProvider.cs

@@ -95,9 +95,10 @@ public interface IHistoryProvider
     /// </param>
     /// <param name="cancellationToken">Request cancellation.</param>
     /// <remarks>
-    ///     Default implementation throws. Only drivers with an event historian (Galaxy via the
-    ///     Wonderware Alarm &amp; Events log) override. Modbus / the OPC UA Client driver stay
-    ///     with the default and let callers see <c>BadHistoryOperationUnsupported</c>.
+    ///     Default implementation throws. Drivers whose backend can serve historical events
+    ///     override: Galaxy (Wonderware Alarm &amp; Events log) and the OPC UA Client driver
+    ///     (forwarding HistoryReadEvents to its upstream server). Raw-only drivers such as Modbus
+    ///     stay with the default and let callers see <c>BadHistoryOperationUnsupported</c>.
     ///
     ///     Note the type asymmetry with <see cref="ReadRawAsync"/> /
     ///     <see cref="ReadProcessedAsync"/> (both use <c>uint maxValuesPerNode</c>): event