[Typo] ES|QL Docs - "using using" in RLIKE

[nicpenning]

From the docs:

Use RLIKE to filter data based on string patterns using using [regular expressions(external, opens in a new tab or window)](https://www.elastic.co/docs/reference/query-languages/query-dsl/regexp-syntax). RLIKE usually acts on a field placed on the left-hand side of the operator, but it can also act on a constant (literal) expression. The right-hand side of the operator represents the pattern.

Surprisingly, if you search all of the Elastic Org for "using using" in code, it is found 20 times!
https://github.com/search?q=org%3Aelastic%20%22using%20using%22&type=code

Not sure where it all needs to be updated, but this might be something to cleanup across the board. I will try my hand at a PR for Elasticsearch docs, but it seems to be pretty complicated since redundant info is found in multiple places.