[texdoc] help msg

[Karl Berry]

1) --help says:
  -a, --alias           Use the alias table.
  -A, --noalias         Don't use the alias table.
It should say (default) on the -a line.
Ditto for whichever of -i/-I is the default.


2) it is standard for the --help message to have --help and --verbose in
the list.
2b) I'd also suggest a blank line before/after the option list,
2c) and putting the synopsis after the usage: line.
2d) It's conventional not to pluralize "OPTION" with the ... (NAME was
not plural).
2e) please state the default mode of operation.  (I'm not actually sure
    what it is.)

Something like:

Usage: texdoc [OPTION]... [NAME]...

Try to find appropriate TeX documentation for the specified NAME(s).
The default is view mode to display the documentation.

With no NAME, it can print configuration information (-f, --files);
the usual --help and --version options are also accepted.

  -w, --view            Use view mode: start a viewer.
[...]
  -M, --machine         Use a more machine-friendly output format.
  
  -f, --files           Print the name of the config files being used.
  -h, --help            Display this help and exit.
      --version         Display version information and exit.

Environment: PAGER, BROWSER, PDFVIEWER, PSVIEWER, DVIVIEWER.
Files: <texmf>/texdoc/texdoc.cnf files; see the -f option.
Home page: http://tug.org/texdoc/
Manual: displayed by `texdoc texdoc'.


Thanks,
Karl