Populate changelog for 0.18.1 release

[antonwolfy]

This PR adds release summary and included changes.

• Have you provided a meaningful PR description?
• Have you added a test, reproducer or referred to an issue with a reproducer?
• Have you tested your changes locally for CPU and GPU devices?
• Have you made sure that new changes do not introduce compiler warnings?
• Have you checked performance impact of proposed changes?
• Have you added documentation for your changes, if necessary?
• Have you added your changes to the changelog?

[github-actions]

Array API standard conformance tests for dpnp=0.18.0=py312h852cfe9_10 ran successfully.
Passed: 1231
Failed: 0
Skipped: 9

[vlad-perevezentsev]

Thank you @antonwolfy