Cross-reference to fmu-dataio documentation

[anders-kiaer]

https://fmu-dataio.readthedocs.io/en/latest/exported_standard_results.html#

fmu-dataio is starting to document how specified standard results should be exported from modules. Currently inplace volumes are documented.

Webviz should perhaps, for each module, list the required and optional data types necessary for it to work, and link/refer to the fmu-dataio documentaiton when it comes to how to export it in their FMU model.