v0.28.1 Release notes

Small emergency release to fix several issues

• Fixed gymnasium.vector as the gymnasium/__init__.py as it isn't imported #403
• Update third party envs to separate environments that support gymnasium and gym and have a consistent style #404
• Update the documentation for v0.28 as frontpage gif had the wrong link, experimental documentation was missing and add gym release notes #405

Full Changelog: v0.28.0...v0.28.1