Docs: Replace Ruby EDI instructions with native EDI

[Jeff Davis]

Evergreen has supported native EDI since 3.0 (see bug 1373690). However, it appears that the official documentation only covers the old and presumably obsolete Ruby-based EDI, e.g.:
http://docs.evergreen-ils.org/3.2/_setting_up_edi_acquisitions.html

The docs should probably updated to cover the new approach. The 3.0 release notes contain some information which may be a useful starting-point:
http://docs.evergreen-ils.org/3.0/_administration.html