document new `remote_folder` input

[ltalirz]

Is your feature request related to a problem? Please describe

It seems to me that since 3a36afb3d0d08d3b5048c4337ab8b59217fbfefd by @sphuber , all CalcJob classes now display a new input: the remote_folder.

Example:

$ verdi plugin list aiida.calculations nwchem.nwchem
Description:

    Base calculation class for NWChem.

    Synthesizes NWChem input file from parameter dictionary and StructureData.

Inputs:
         parameters:  required  Dict                    Input parameters
          structure:  required  StructureData           The input structure, with or without a cell
           add_cell:  optional  Bool                    The input structure, with or without a cell
               code:  optional  AbstractCode            The `Code` to use for this job. This input is required, unless the `remote_ ...
           metadata:  optional                          
      remote_folder:  optional  RemoteData              Remote directory containing the results of an already completed calculation ...
     restart_folder:  optional  RemoteData, FolderData  Remote directory of a completed NWChem calculation to restart from.

Here, the remote_folder is defined by aiida-core, while the restart_folder is defined by the plugin.

Describe the solution you'd like

I think this new input should be explained more extensively in both the documentation for users and the one for plugin developers.

I tried using this input to do restarts and got somewhat confusing results.

[sphuber]

That input is meant for importing calculations that have been completed without AiiDA. See AEP 004 https://github.com/aiidateam/AEP/blob/master/004_calcjob_importer/readme.md I didn't have the time to document at the point of merging and lost track of it since but you are right I should still document this. Coincidentally I was just working this wee on the implementation for PwCalculation. Once I finish that I will document the functionality in aiida-core