Fix nightly docs link, update JDBC driver link
The nightly docs location seems to have moved, and the CNAME/redirect that was working before is broken, so fix it to point to the right link.
Furthermore point to the new JDBC driver release on the site.
Change-Id:If17ec8dbd1de435c9a0c6e9f4d3b71c6ede2a5b1 Reviewed-on: https://asterix-gerrit.ics.uci.edu/c/incubator-asterixdb-site/+/20938 Reviewed-by: Ian Maxon imaxon@apache.org