Recently hit an issue with this procedure when it turned out that the directoryPerDB option was enabled when the node was in a replica set, but was not contained in the configuration file (instead it was passed as a command line option via the Windows service). If you fail to include directoryPerDB when starting as a standalone there is no error, and you can complete the procedire, but you will end up creating a new local database etc.

I would suggest adding a tip or warning, something like the following (with appropriate linkage) below the instruction to start the node as a standalone on a different port (not submitting as a pull request, because I am not sure about how best to frame it, nor how best to link to the configuration option):

.. tip:: Be careful to ensure that you include all necessary
     options when starting as a standalone instance. In particular,
     the directoryPerDB option must be specified if used when the
     process is part of a Replica Set.   Failure to do so will not
     cause errors, but the procedure will not succeed in resizing
     the oplog.