textproc/po4a: Update to 0.62
- Add LICENSE_FILE
- Move to GitHub (new project's repository)
- Improve pkg-descr description along with the new website
Changelog: https://github.com/mquinson/po4a/blob/v0.62/NEWS
Approved by: garga (maintainer)
Differential Revision: https://reviews.freebsd.org/D28653