guide: Data Management

[jorgeorpinel]

Data Mgmt is simple enough that covering it in the Get Started and Command Reference has thus far been enough. But having a group of existing content under this "Category" could achieve some goals:

• Help reorg existing content (e.g. Large Dataset Optimization, Managing External Data, etc.)

• Include Remote usage details? See guide: extract remote add/modify details from cmd ref. #2866
  Or should that be part of a Configuration guide? (rel. guide: extract part of theconfig cmd ref. #340)

• WIP: What else?

[jorgeorpinel]

WDYT @iesahin @shcheklein ?

p.s. I'm not seeing this as a priority but if a very quick reorg of existing content can be done in a day we should feel free to go for it as a first step here.

[jorgeorpinel]

Closing in favor of #2856