[mutasim-rehman]

Link to issue

Refs #5632.

Description of change

Summary

Refs #5632.

• Adds a Filled Areas with Missing Data section to doc/python/filled-area-plots.md.
• Documents the current tozeroy/tozerox behavior around None/NaN gaps in SVG scatter traces.
• Demonstrates separating consecutive non-missing runs into tozeroy traces that share a legendgroup, with only the first trace shown in the legend.
• Links to upstream plotly/plotly.js#2736.

Investigation and scope

The Python Scatter object preserves missing values (None serializes to null), and the actual fill drawing occurs in plotly.js. The renderer-level fix is being handled in plotly/plotly.js#8140. This PR is intentionally documentation-only, not a substitute for the rendering fix.

Demo

The documentation example is included in the changed page; no screenshot is applicable.

Testing strategy

All 10 Python examples on the page were run with fig.show() disabled and completed without errors. The new example preserves the input values and splits y=[2, 3, 4, None, None, 5, 6, 4, None, 3] into three correctly grouped traces. A full documentation build and browser rendering were not run.

Additional information (optional)

The final isolated point is shown as a marker with no area fill, as expected. The docs section is limited to SVG scatter traces.

Guidelines

• I have reviewed the pull request guidelines and the Code of Conduct and confirm that this PR follows them.
• I have added an entry to the changelog if needed (not required for documentation PRs).