How do I create an app-specific password for iCloud? I'm trying to try out BusyCal, but it requires an app-specific password, and provides an outdated link to old information about how to do this.

The page refers to an "App Specific Passwords section" under the Security settings of the Apple ID site's account management page.  This section does not exist under Security, or anywhere else on that page.  

There is almost certainly still a way to create app-specific passwords, but even Apple can't keep their help up-to-date, and even a company whose main product depends on users finding this information can't provide it, so Stack Exchange seemed like the best place to turn.

How (and where) do I create an app-specific password these days?
The missing information was provided by @GordonDavisson (and if he wants to post an answer I will accept his instead of mine):


  To generate and use app-specific passwords, your Apple ID must be protected with two-factor authentication.


This is actually on the Apple Help page, but oddly not included in the section "How to generate an app-specific password" (even though it was the missing step for exactly that question) but instead buried between an explanation of what an app-specific password is (which was of no value to me) and fine print about different OS versions.   I used the headers to skip right to the relevant information (which is what headers are generally for) and didn't guess that a critical piece of information would be placed elsewhere.