add swarm plot to the scatter documentation

[rl-utility-man]

This is inspired by #5087. Many thanks to @suterberg for inspiring it and getting me started.

If your PR modifies code of the plotly package, we have a different checklist
below :-).

Documentation PR

• [ Y] I've seen the doc/README.md file
• [ Y] This change runs in the current version of Plotly on PyPI and targets the doc-prod branch OR it targets the main branch
• [ N/A] If this PR modifies the first example in a page or adds a new one, it is a px example if at all possible
• [ Y] Every new/modified example has a descriptive title and motivating sentence or paragraph
• [ Y] Every new/modified example is independently runnable
• [ Y] Every new/modified example is optimized for short line count and focuses on the Plotly/visualization-related aspects of the example rather than the computation required to produce the data being visualized
• [ Y] Meaningful/relatable datasets are used for all new examples instead of randomly-generated data where possible
• [ N/A] The random seed is set if using randomly-generated data in new/modified examples
• [ Y] New/modified remote datasets are loaded from https://plotly.github.io/datasets and added to https://github.com/plotly/datasets
• [ Y] Large computations are avoided in the new/modified examples in favour of loading remote datasets that represent the output of such computations
• [ Y ] Imports are plotly.graph_objects as go / plotly.express as px / plotly.io as pio
• [ Y ] Data frames are always called df
• [ it's as high as it can logically go ] fig = <something> call is high up in each new/modified example (either px.<something> or make_subplots or go.Figure)
• [ Y ] Liberal use is made of fig.add_* and fig.update_* rather than go.Figure(data=..., layout=...) in every new/modified example
• [ Y ] Specific adders and updaters like fig.add_shape and fig.update_xaxes are used instead of big fig.update_layout calls in every new/modified example
• [ Y ] fig.show() is at the end of each new/modified example
• [ Y ] plotly.plot() and plotly.iplot() are not used in any new/modified example
• [ Y ] Hex codes for colors are not used in any new/modified example in favour of these nice ones

Code PR

• I have read through the contributing notes and understand the structure of the package. In particular, if my PR modifies code of plotly.graph_objects, my modifications concern the codegen files and not generated files.
• I have added tests (if submitting a new feature or correcting a bug) or
  modified existing tests.
• For a new feature, I have added documentation examples in an existing or
  new tutorial notebook (please see the doc checklist as well).
• I have added a CHANGELOG entry if fixing/changing/adding anything substantial.
• For a new feature or a change in behaviour, I have updated the relevant docstrings in the code to describe the feature or behaviour (please see the doc checklist as well).

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[rl-utility-man]

I need to develop logic to "look left", spot any overlapping markers and increment the bin size potentially repeatedly if needed to avoid collisions.