feat(examples): Add storage/nvsgen example

Showcases the use of `nvs_create_partition_image` CMake function
Remove mentions of NVS multipage blob version 1 so it's not encouraged

examples/storage/nvsgen/pytest_nvsgen_example.py

@@ -0,0 +1,11 @@
+# SPDX-FileCopyrightText: 2023 Espressif Systems (Shanghai) CO LTD
+# SPDX-License-Identifier: Unlicense OR CC0-1.0
+
+import pytest
+from pytest_embedded import Dut
+
+
+@pytest.mark.esp32
+def test_nvsgen_example(dut: Dut) -> None:
+    dut.expect('Reading values from NVS', timeout=10)
+    dut.expect('Reading values from NVS done - all OK', timeout=10)