[DOCS] Release version updated to 3.0
[DOCS] Release version updated to 3.0

Change-Id: I511235e543018b322c12132d3470ceda01566613
Cherry-picks: not for 2.x.
Reviewed-on: http://gerrit.cloudera.org:8080/10084
Reviewed-by: Alex Rodoni <b46da68bf9b818cec7052f7cdfe9b3e69485676b@cloudera.com>
Tested-by: Impala Public Jenkins <039b6b20426ff68ebe492b3021890d8c8fd010c9@cloudera.com>

cloudera/Impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,cloudera/Impala