Fix section links in reference homepage

[khantiRindani]

Hi team, thank you so much for putting together this amazing library and docs. It's been greatly beneficial for me.

Issue Description:

While navigating through docs, I found some broken links and wanted to suggest changes on them.

Affected page: https://plotly.com/javascript/reference/index

Issue Demo:

Solution Demo:

Capturing demo by making local html changes through browser dev tools.