files: remove assertion on recursive onChange

See discussion in

  https://github.com/nix-community/home-manager/pull/2031

modules/files.nix

@@ -39,17 +39,6 @@ in
   };
 
   config = {
-    assertions = [(
-      let
-        conflicts = mapAttrsToList (n: v: n)
-          (filterAttrs (n: v: v.recursive && v.onChange != "") cfg);
-      in {
-        assertion = conflicts == [];
-        message = ''
-          Cannot use 'home.file.<name>.onChange' when 'home.file.<name>.recursive' is enabled:
-              ${concatStringsSep ", " conflicts}'';
-      })];
-
     lib.file.mkOutOfStoreSymlink = path:
       let
         pathStr = toString path;

modules/lib/file-type.nix

@@ -83,8 +83,8 @@ with lib;
             <emphasis>after</emphasis> the new files have been linked
             into place.
             </para><para>
-            Note, this option cannot be used when <literal>recursive</literal>
-            is enabled.
+            Note, this code is always run when <literal>recursive</literal> is
+            enabled.
           '';
         };