[ONNX FE] Add operations in the documentation page - SequenceAt, SplitToSequence (#32991)

The operations that are being documented in this delivery have been
included and successfully merged in OpenVINO 2025/4.

### Details:
 - SequenceAt support declared
 - SplitToSequence support declared

### Tickets:
 - [CVS-176808](https://jira.devtools.intel.com/browse/CVS-176808)

Author: bumbosiepsak

docs/articles_en/documentation/compatibility-and-support/supported-operations.rst

@@ -218,6 +218,7 @@ Data as of OpenVINO 2024.4, 18 Oct. 2024.
        ScatterElements
        ScatterND
        Selu
+       SequenceAt
        Shape
        Shrink
        Sigmoid
@@ -231,6 +232,7 @@ Data as of OpenVINO 2024.4, 18 Oct. 2024.
        Softsign
        SpaceToDepth
        Split
+       SplitToSequence
        Sqrt
        Squeeze
        STFT