Fix heading levels

docs/usage/esql.asciidoc

@@ -23,7 +23,7 @@ use cases.
 
 [discrete]
 [[esql-how-to]]
-==== How to use the ES|QL API
+=== How to use the ES|QL API
 
 The {es-docs}/esql-query-api.html[ES|QL query API] allows you to specify how
 results should be returned. You can choose a
@@ -40,7 +40,7 @@ The following example gets ES|QL results as CSV and parses them:
 
 [discrete]
 [[esql-consume-results]]
-==== Consume ES|QL results
+=== Consume ES|QL results
 
 The previous example showed that although the raw ES|QL API offers maximum
 flexibility, additional work is required in order to make use of the
@@ -62,7 +62,7 @@ allows efficient processing of column data.
 
 [discrete]
 [[esql-custom-mapping]]
-==== Define your own mapping
+=== Define your own mapping
 
 Although the mappers provided by the .NET client cover many use cases, your
 application might require a custom mapping.