allow disable resource_monitor appending with nipype option (amend to last commit)

Author: oesteban

doc/users/config_file.rst

@@ -164,7 +164,7 @@ Execution
 
 *resource_monitor_append*
     Append to an existing ``resource_monitor.json`` in the workflow ``base_dir``.
-    (unset by default, possible values: ``true``, ``false``,
+    (unset by default, possible values: ``true`` or ``false``,
     will append unless explicitly set to ``false``).
 
 Example