How does conan-docs implement its version switcher?

### Problem Description

According to my understanding, Read The Docs will provide built-in Version/Langauge Switchers. However, it seems that Conan doesn't use RTD. Therefore, I wonder how conan-docs implement its version switcher?

Take CMake Documentation for example. It provides its own version switcher by using [version_switch.js](https://cmake.org/cmake/help/version_switch.js).

And it seems that the locally built documentation won't display the version switcher. How does Conan setup its version switcher?

### Screenshots



Start with the version_switch.js implementation linked in the issue and inspect the Conan documentation build and publishing configuration to identify how the hosted switcher is supplied. Compare that with a locally built documentation site. Done means documenting the switcher's source, setup, and why it is absent from local builds.

Written by the indexing model from the issue text.