- Rename x86-64.sgml to amd64.sgml (no repo copy since there isn't much interesting history to save).
- Update the status of the FreeBSD/amd64 port.
- Sort the platform list alphabetically.
- Add dummy redirect page from x86-64.sgml to amd64.sgml. 
Not objected to by: -www 
Reviewed by: obrien (current FreeBSD/amd64 port status)
Approved by: ceri (mentor)