The easiest way to get documentation for LaTex packages on Debian is
using the texdoc program. Unfortunately, as a TexLive novice I found I
didn't know what that involved. It was claimed on the internet that
running something like texdoc classes would cause the
documentation on the standard tex classes to pop up, but this wasn't working
for me.
Texlive packages are split across a number of Debian packages, and each
Debian package has a corresponding documentation package. So, for
example, to get the documentation for siunitx, which is in
texlive-science, texlive-science-doc is needed.
This much was explained
somewhere else online, but it can take a bit of head-scratching to work
out which Debian package a given LaTeX package will be under. One way to
work out which doc package is needed is to use apt-file. If
texdoc source2e isn't finding anything, then
# apt-file update
$ apt-file find source2e will tell you the package you're looking for is
texlive-latex-base-doc
Even having installed the *-doc package, texdoc still wasn't finding
it. The reason for this is that the index for texdoc needed rebuilding.
I think this is a sign of a packaging error, since that ought really to
happen any time a new texlive-*-doc package is installed. To do it by
hand, it's a simple matter of
# mktexlsrexecuted as root. This finally got it to find the correct documentation and I had no option but to get back to writing my final project report.