[MetaCRS] Motion: Promote PROJ 5.0.0RC6 to Final

[Howard Butler]

All,

With 6 release candidates, PROJ is finally ready to go 5.0.0. I motion to promote the release to final.

Release Notes: https://github.com/OSGeo/proj.4/blob/master/NEWS
Release Plan:  https://github.com/OSGeo/proj.4/milestones 

Kristian Evers is now the maintainer of the project, and along with Thomas Knudsen and a bunch of other contributors, has led the development push to make 5.0.0 a reality. It is a substantial refresh that includes a new and modernized API, completely refactored the geodetic transformation capabilities of PROJ, and tons of additional documentation content. I would like to congratulate them on an effort well done!

The release process at the moment requires a release motion through MetaCRS. 

Howard