message: Make paragraph about running IOManager read on smaller number of
  processors into a warning.
diff: @@ -61,8 +61,11 @@ processors. If ``write()`` was executed on N ranks and ``read()`` is called
  while running on M ranks (M > N), then data will be read into ranks 0 to N-1,
  and all ranks higher than N-1 will receive no data.
  +.. warning::
  If ``read()`` is called in an attempt to read data that was created on a
  larger number of processors than the current run, an error will occur.
  + Support for this type of usage is intended to be added in future
  + releases.
  In the following example, an IOManager is created and used to write the contents
  of the Group "root" in parallel.
  