bug#6591: 24.0.50; incorrect doc for `catch'

[Drew Adams]

> BODY... or FORM... or SEXP... or whatever you call it matches the
> arguments that follow TAG.

OK, that's also Eli's interpretation of `...'.
In that case, BODY is _not_ repeated (repeatable).
And in that case, FORM... or SEXP... would not be appropriate.
The body is not a sexp.

This interpretation of `...' is unconventional, atypical.  Outside Emacs, `...'
typically means repetition of what it follows - in this case BODY.  It's fine
for Emacs to have an unusual syntax convention, but it needs to be documented.