bug#15152: put-char documentation

[Josep Portella Florit]

Hi!

There is another little error in `doc/ref/api-io.texi'.  The
documentation for put-char ends abruptly:

@deffn {Scheme Procedure} put-char port char
Writes @var{char} to the port. The @code{put-char} procedure returns
@end deffn

It should be:

@deffn {Scheme Procedure} put-char port char
Writes @var{char} to the port. The @code{put-char} procedure returns
an unspecified value.
@end deffn


Josep