[tldoc] offer of help with an install guide for the unsophisticated windows user

[Karl Berry]

    5) Confusion when running `pdflatex sometexfile' at the command prompt
        didn't work. This one is partly my fault; I've never used any
        version of LaTeX on Windows, and I'd anticipated that, if
        somefile.tex is present, the command line to run latex on it would
        not need to specify the `.tex' extension.

That is certainly the case.  The Windows binaries are no different from
the Unix binaries in this regard, and never have been.

So I don't know why it failed, but it's not because the windows latex
doesn't add .tex ...