man: sd_journal_stream_fd: no, fds are not shared (#7926)

man: sd_journal_stream_fd: no, fds are not shared (#7926)

sd_journal_stream_fd() does not return the same file descriptor across
different calls.  It can't possibly do so, because the file descriptor
is created using certain parameters passed by the caller.

Also the implementation clearly isn't doing this, it's just connecting
to a unix socket.

It opens exactly one file descriptor, and does not close it unless there
is a write failure.  Nothing like "temporarily multiple file descriptors
may be open".