set dbfit download link to github/*/releases in getting-started docs
Add github repository in _config.yml
to use it for building links relative to repo
docs - refactor links to use site.repository instead of hardcoded urls
docs - resources: move a description out of a link
(in alignment with the rest links)
Merge pull request #202 from dbfit/fix-dbfit-download-link-in-getting-started-docs

set dbfit download link to github/*/releases in getting-started docs