* added DatabaseSystems in free-course-hi.nd and two courses in it
* changed Database Systems to Databases
* Update free-courses-hi.md
* Update courses/free-courses-hi.md
Co-authored-by: Eric Hellman <eric@hellman.net>
* Update courses/free-courses-hi.md
Co-authored-by: Eric Hellman <eric@hellman.net>
Co-authored-by: Eric Hellman <eric@hellman.net>