[#21] Update README and add AGPL 3.0 license
- Remove note on this being Alpha software.
- Remove YottaDB requirement. This software doesn't care if it runs on YottaDB or for that matter, GT.M.
- Simply say we need Octo.
- Improve copy-pastable instructions to set-up DUZ so that non-VistA users can easily use this.
- Mention that mapping a single file doesn't quite work.
- Update the function list and install instructions so that it's correct. Previously, the install instructions were not complete, and the list had omissions and wrong names for functions.
- Add AGPL 3.0 license in COPYING file.