Breaking change note for the text import/export APIs

See #6294

Author: roji

conceptual/Npgsql/release-notes/10.0.md

@@ -48,3 +48,7 @@ This is in line with other .NET API (like `NetworkStream.ReadTimeout`), where `T
 ### `PostgresException.BatchCommand` is `null` by default
 
 This prevents accidental leak of queries and parameters when exceptions are logged. To change this behavior you can set `IncludeFailedBatchedCommand` in connection string to `true`.
+
+### NpgsqlConnection.BeginText{Import,Export}Async now return NpgsqlCopyTextReader instead of TextWriter
+
+The methods to start a text import/export operation have been changed to return a more specific `NpgsqlCopyTextReader`, rather than a general `TextWriter`; this was done since `NpgsqlCopyTextReader` exposes some additional APIs to allow cancelling and setting the timeout on a COPY operation. Since `NpgsqlCopyTextReader` extends `TextWriter`, this is a binary breaking change only - recompiling against the new version of Npgsql should work without any source changes.