docs/87073: New article: Maintaing and contributing to the FreeBSD Ports Collection

[Sam Lawrance]

I have updated the shar and html preview.  Changes:
- wrap, indent and format according to FDP primer
- included a number of small rewording suggestions from eivind

http://people.freebsd.org/~lawrance/contributing-ports/article.html
http://people.freebsd.org/~lawrance/contributing-ports/contributing-ports.sh