Add Scroll Depth tracking on Plausible

[elijames-codecov]

Problem Statement

Matt Henderson and I have added Scroll Depth tracking to the marketing site and blog on Plausible, and Liza would like this expanded to docs.

Solution Brainstorm

Here are the code on the blog and some additional insights. We currently have it setup with a custom property readProgress connected to the goal Read Progress (both are setup in Docs Plausible to start collecting data).

[elijames-codecov]

cc @lizokm

[getsantry]

Assigning to @getsentry/support for routing ⏲️

[a-hariti]

We don't have Plausible analytics on docs

should we add that @lizokm ?

[elijames-codecov]

@a-hariti - Plausible analytics is installed on the Docs site. It's been there for at least a year.