Clarified about rsync in 15-transferring-files.md

[cdkharris]

I worked a quick example to check my sanity.

The example given just above this text is correct, but the text below didn't match it.

What occurs with the given example:

[myriad][ccaech0@login13 ~]$ ls example_dir
bar  foo
[myriad][ccaech0@login13 ~]$ rsync -avzP example_dir kathleen:example_dir
sending incremental file list
example_dir/
example_dir/bar
              0 100%    0.00kB/s    0:00:00 (xfr#1, to-chk=1/3)
example_dir/foo
              0 100%    0.00kB/s    0:00:00 (xfr#2, to-chk=0/3)

sent 178 bytes  received 58 bytes  52.44 bytes/sec
total size is 0  speedup is 0.00
...
[kathleen][ccaech0@login01 ~]$ ls example_dir/
example_dir
[kathleen][ccaech0@login01 ~]$ ls example_dir/example_dir/
bar  foo
[kathleen][ccaech0@login01 ~]$ rm -rf example_dir/*

What occurs in the discussed, but not shown example (/ appended to the source):

[myriad][ccaech0@login13 ~]$ rsync -avzP example_dir/ kathleen:example_dir/
sending incremental file list
./
bar
              0 100%    0.00kB/s    0:00:00 (xfr#1, to-chk=1/3)
foo
              0 100%    0.00kB/s    0:00:00 (xfr#2, to-chk=0/3)

sent 157 bytes  received 57 bytes  38.91 bytes/sec
total size is 0  speedup is 0.00
...
[kathleen][ccaech0@login01 ~]$ ls example_dir/
bar  foo