Explain compatiblity libraries

Documentation currently says

> Applications compiled on one major version of FreeBSD are expected to run on subsequent major versions of FreeBSD if compatiblity libraries are installed. Example: An application compiled on FreeBSD 3.2 is expected to run on FreeBSD 14 if compatiblity libraries are installed.

We should explain this using a practical example.
https://www.cinelerra-gg.org/freebsd-package/ seems to require siome libraries in versions older than what currently ships with helloSystem.

What are the exact steps to make it run?

Related:
https://github.com/helloSystem/launch/issues/1#issuecomment-798869996

Start with the compatibility-library statement in the issue, the Cinelerra-GG FreeBSD package page, and the related launch comment. Determine the exact steps and older library versions needed to run the application on helloSystem, then document that practical example with enough detail to reproduce it.

索引モデルが issue の本文から書いたものです。