Put docs in content/ dir...

Change-Id:If97ac8dad8df435c9a0c15ef4d7a7e615bb3ecd3
Reviewed-on: https://asterix-gerrit.ics.uci.edu/c/incubator-asterixdb-site/+/12364
Reviewed-by: Ian Maxon <imaxon@uci.edu>
81 files changed