Manual github_io website file listings say "tree: not found" [BUG]

[TamaMcGlinn]

Describe the bug

The manual is evidently built by a script and where it is supposed to list files, it instead says:

/usr/bin/sh: 1: tree: not found

See this page for example:

[johentsch]

Ouch, thanks for pointing this out, @TamaMcGlinn! Apparently the bug comes from commands being executed at build-time without the files being present on the ReadTheDocs runner. This week, I don't have time to look into this, but as a workaround, there is a working copy of the page here: https://ms3.readthedocs.io/en/stable/manual/index.html