Fix version order for breaking changes docs

docs/reference/migration/index.asciidoc

@@ -18,10 +18,10 @@ See <<setup-upgrade>> for more info.
 --
 include::migrate_3_0.asciidoc[]
 
-include::migrate_2_1.asciidoc[]
-
 include::migrate_2_2.asciidoc[]
 
+include::migrate_2_1.asciidoc[]
+
 include::migrate_2_0.asciidoc[]
 
 include::migrate_1_6.asciidoc[]