Adding docs for grouped nav advanced setting (#57013)

* Adding docs for grouped nav advanced setting

docs/management/advanced-options.asciidoc

@@ -69,6 +69,9 @@ into the document when displaying it.
 `metrics:max_buckets`:: The maximum numbers of buckets that a single
 data source can return. This might arise when the user selects a
 short interval (for example, 1s) for a long time period (1 year).
+`pageNavigation`:: The style of navigation menu for Kibana.
+Choices are Individual, the legacy style where every plugin is represented in the nav,
+and Grouped, a new format that bundles related plugins together in nested navigation.
 `query:allowLeadingWildcards`:: Allows a wildcard (*) as the first character
 in a query clause. Only applies when experimental query features are
 enabled in the query bar. To disallow leading wildcards in Lucene queries,