[DOCS] SQL: Update link for supported regex in RLIKE docs (#55830)

The`RLIKE` function docs points users to [Java’s Pattern class doc][0]
for regular expression syntax. However, these docs include shorthand
character classes, such as `[\d]`, `[\s]`, and `[\w]`. These character
classes are not supported in Elasticsearch, which may confuse users.

This updates the SQL `RLIKE` docs to refer to the ES [regular expression
syntax docs][1], which only documents supported syntax.

[0]: https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/regex/Pattern.html
[1]: https://www.elastic.co/guide/en/elasticsearch/reference/master/regexp-syntax.html

Relates to #55231

Author: jrodewig

docs/reference/sql/functions/like-rlike.asciidoc

@@ -72,8 +72,7 @@ RLIKE constant_exp <2>
 This operator is similar to `LIKE`, but the user is not limited to search for a string based on a fixed pattern with the percent sign (`%`)
 and underscore (`_`); the pattern in this case is a regular expression which allows the construction of more flexible patterns.
 
-For more details about the regular expressions syntax, https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/regex/Pattern.html[Java's Pattern class javadoc]
-is a good starting point.
+For supported syntax, see <<regexp-syntax>>.
 
 [source, sql]
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