docs: fix typos in docstrings and example descriptions

[Avicennasis]

Summary

Fixes 17 documentation typos across docstrings and sphinx-gallery example headers. Documentation only — no functional or API changes, and no identifiers renamed.

Docstring fixes

• src/ansys/fluent/visualization/graphics/graphics_objects.py: Pathlines.display() was documented as """Display mesh graphics.""" — a copy-paste from Mesh.display() directly above it. Now reads """Display pathlines graphics.""".
• graphics_objects.py: from ansys.fluent.visualization import Graphics → single space, in all four .. code-block:: python examples in the file.
• plotter/pyvista/renderer.py, plotter/matplotlib/renderer.py: Matplot lib figure. → Matplotlib figure.
• plotter/pyvista/renderer.py, plotter/matplotlib/renderer.py, graphics/pyvista/renderer.py: Data consists the list of x and y values → Data consists of the list ...
• plotter/pyvista/renderer.py: pyvista chart 2D plotter → PyVista chart 2D plotter (x2), matching the spelling in this repo's own doc/styles/config/vocabularies/ANSYS/accept.txt.
• graphics/graphics_windows.py, graphics/graphics_windows_manager.py, visualization_windows_manager.py: overlay : bool, Optional → bool, optional, matching numpydoc and the session_id : str, optional line directly above it in the same docstrings.

Example-header fixes

• examples/00-post_processing/post_processing_callbacks_and_animation.py and post_processing_plotter_apis_context_manager.py: **Key Features was missing its closing **, so the heading renders as literal asterisks instead of bold. post_processing_plotter_apis.py already has the correct **Key Features**.

Additionally noticed

Six of the above were not in the set I originally set out to fix; I included them because each is the same string in a file that would have looked arbitrary to leave behind:

• Matplot lib and Data consists the in plotter/matplotlib/renderer.py
• Data consists the in graphics/pyvista/renderer.py
• overlay : bool, Optional in graphics/graphics_windows_manager.py
• the unclosed **Key Features in post_processing_plotter_apis_context_manager.py
• two of the four import Graphics occurrences in graphics_objects.py

Happy to split any of these out if you would rather keep the change narrower.

Deliberately not changed

• Pyvista → PyVista appears 14 more times across five examples/ headers. Your accept.txt says PyVista, so these look wrong too, but sweeping them felt out of proportion for a typo PR — happy to add them on request.
• if self._single_window and val == False: in config.py. Flagged to me as non-PEP8, but it is executable code rather than documentation, so I left it alone.

Verification

Each replacement was applied byte-wise with a uniqueness assertion and a file-length delta check, so the diff is exactly 17 changed lines with no line-ending churn. All nine touched files byte-compile, and no edited line exceeds the max-line-length = 88 in .flake8.