Docs: Note that include_in_parent/root does not apply to geo-shape fields

Closes #10653

docs/reference/mapping/types/nested-type.asciidoc

@@ -139,6 +139,10 @@ Nested fields may contain other nested fields.  The `include_in_parent` object
 refers to the direct parent of the field, while the `include_in_root`
 parameter refers only to the topmost ``root'' object or document.
 
+NOTE: The `include_in_parent` and `include_in_root` options do not apply
+to <<mapping-geo-shape-type,`geo_shape` fields>>, which are only ever
+indexed inside the nested document.
+
 Nested docs will automatically use the root doc `_all` field only.
 
 .Internal Implementation