Changed Usage in the rsync --help message to indicate how there can be

Changed Usage in the rsync --help message to indicate how there can be
multiple SRCs.  Also moved the --suffix option to show up right after
--backup and included the default backup suffix and block size along with
their corresponding options rather than at the end.  Copied the new help
message to rsync.yo and README and used the Usage also in the SYNOPSIS
section at the top of rsync.yo rather than the different one that used
"path" instead of SRC and DEST.  That last change was inspired by a
suggestion from Michael Bleyer in PR #1523.