The current help text talks about two forms to run this command,
but only one is mentioned. This commit tries to clarify that the
function behaves differently when called without argument.
Usage: complete [<cword> <word>...]
-In the first form, the command prints all possible completions to stdout.
-This can be used from the completion function of the shell.
+When executed without argument the command writes bash code to
+stdout. This code is suitable to be evaled from .bashrc to enable
+completion.
-Completion code suitable to be evaled is written to stdout if no argument
-was given.
+If at least one argument is given, all possible completions are
+written to stdout. This can be used from the completion function of
+the subcommand.
"
_com_help()