GeezerVison

Closes #1183.

This updates the lqe and dlqe docstrings to describe the steady-state estimation error covariance minimized by the estimator, instead of saying only that the state estimate minimizes expected squared error.

I avoided adding a runtime behavior change or changing generated docs directly.

Validation:

• python -m ruff check control/stochsys.py
• python -m pytest control/tests/stochsys_test.py -q -> 25 passed, 2 skipped
• python -m numpydoc render control.stochsys.lqe
• python -m numpydoc render control.stochsys.dlqe
• $env:PYTHONPATH='..'; python -m pytest test_sphinxdocs.py::test_config_defaults -q -> 1 passed, 4 warnings

Known unrelated local docs issues:

• python -m numpydoc validate control.stochsys.lqe/control.stochsys.dlqe reports pre-existing docstring style findings.
• The full Sphinx docs test file needs generated docs/CWD setup that is not present in this fresh clone.

AI Disclosure: Codex (ChatGPT 5.5) was used during code navigation, initial drafting, and PR text preparation. All logic, code changes, and test cases have been manually reviewed, verified, and tested locally by the author in accordance with the NumPy AI Policy.