[DOCS] Correct info about REGEXP
[DOCS] Correct info about REGEXP

Change-Id: I6920003c3903bfd6417a530c3785de9e5676a9dd
Reviewed-on: http://gerrit.cloudera.org:8080/10518
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