chore(docs): Updated docs.elgg.org links to point to learn.elgg.org

fixes #6784
Merge pull request #7551 from jdalsem/old-docs-links

chore(docs): Updated docs.elgg.org links to point to learn.elgg.org
chore(readme): Added Read the docs build status badge to the README.md
chore(readme): Switched badges to point to 1.9 branch
Merge pull request #7566 from Srokap/readthedocs_badge

Point all the badges at proper branch for 1.9
chore(i18n): update translations
chore(release): v1.9.6
Merge pull request #7573 from Srokap/release-1.9.6

Release 1.9.6
chore(docs): update root docs to point to learn.elgg.org

ref #7576