[DOCS] Remove `gateway.auto_import_dangling_indices` setting (#78280)

Adds an 8.0 breaking change for PR #59698.

docs/reference/migration/migrate_8_0/settings.asciidoc

@@ -298,4 +298,21 @@ allocation can be disabled by setting
 *Impact* +
 Discontinue use of the deprecated setting.
 ====
+
+[[auto-import-dangling-indices-removed]]
+.The `gateway.auto_import_dangling_indices` setting has been removed.
+[%collapsible]
+====
+*Details* +
+The `gateway.auto_import_dangling_indices` cluster setting has been removed.
+Previously, you could use this setting to automatically import
+{ref}/modules-gateway.html#dangling-indices[dangling indices]. However,
+automatically importing dangling indices is unsafe. Use the
+{ref}/indices.html#dangling-indices-api[dangling indices APIs] to manage and
+import dangling indices instead.
+
+*Impact* +
+Discontinue use of the removed setting. Specifying the setting in
+`elasticsearch.yml` will result in an error on startup.
+====
 //end::notable-breaking-changes[]