Describe the bug
The type specification for the ExtraFiles option in systools:make_tar/2 has the order of the tuple elements backwards.

To Reproduce

1> ls("foo.appup").
foo.appup     
ok
2> systools:make_tar("foo-0.1.0", [{extra_files, [{"lib/foo-0.1.0/ebin/foo.appup", "foo.appup"}]}]).
Cannot add file lib/foo-0.1.0/ebin/foo.appup to tar file - lib/foo-0.1.0/ebin/foo.appup: no such file or directory
error

Expected behavior
The file cse.app should be added to the release package tar file as lib/foo-0.1.0/ebin/foo.appup.

3> systools:make_tar("foo-0.1.0", [{extra_files, [{"foo.appup", "lib/foo-0.1.0/ebin/foo.appup"}]}]).
ok

Affected versions
OTP 27

Additional context
This is a documentation error only (unless you'd rather change the implementation to match the existing documentation).