By default, ReadTheDocs (RTD) shows the 'latest' version of a package's Sphinx-generated documentation that tracks the master branch. This can be confusing to users, who most likely will have the most recent release of the package installed. Thus, they may see something in the documentation that is specific to unreleased features, and does not match up with the version of the package they have installed. A similar problem is with people seeing the documentation for an old release (most likely through a link on Google).
There are two builtin-settings on RTD that help with this, and that should be enable for any package that has had a "stable" release:
Show the "stable" version by default: in the RTD "Admin" tab, select "Advanced Settings" and switch "Default version" from "latest" to "stable"
Show warnings for old version: In the same "Advanced Settings", check the "Show version warning" box
See the documentation of the
krotov package for an example of how this looks: