Visualizer.poll_events() — documentation missing important details

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### Describe the issue

In 0.17.0 the [documentation of open3d.visualization.Visualizer.poll_events()](http://www.open3d.org/docs/release/python_api/open3d.visualization.Visualizer.html?highlight=poll_events#open3d.visualization.Visualizer.poll_events) says:

> **poll_events**(_self_)
> > Function to poll events
> >
> > Returns
> > > bool

which is arguably short on details. The factoid that it returns a bool was enough of a hint for me to try experiments to get the functionality I was looking for:

while(vis.poll_events()):
...

I suggest the [doc](http://www.open3d.org/docs/release/python_api/open3d.visualization.Visualizer.html?highlight=poll_events#open3d.visualization.Visualizer.poll_events) say something like:

> **poll_events**(_self_)
> > Function to poll for and handle events. Handles mouse movement and clicks, plus single key commands during a visualization loop. Normally returns `True`. Returns `False` when visualization loop should exit.
> >
> > Returns
> > > bool

I am not familiar enough with Open3D to feel confident making a pull request. But if someone can provide both a reality check on my doc details and some hints about where to edit, I am happy to make an attempt.

### Steps to reproduce the bug

```python
Just open the [doc](http://www.open3d.org/docs/release/python_api/open3d.visualization.Visualizer.html?highlight=poll_events#open3d.visualization.Visualizer.poll_events)
```

### Error message

none

### Expected behavior

doc would explain functionality of Visualizer.poll_events()

### Open3D, Python and System information

```markdown
- Operating system: macOS 12.6.4
- Python version: Python 3.10.10 (main, Mar 21 2023, 13:41:05) [Clang 14.0.6 ]
- Open3D version: Open3D 0.17.0
- System architecture: apple-silicon
- Is this a remote workstation?: no
- How did you install Open3D?: pip over a conda env
- Compiler version
```

### Additional information

_No response_