Add documentation for dataloader

[peniqliotuv]

I saw in this PR #259 that the Table constructor accepts a dataloader prop, but I can't find any references examples in the docs. Although dataloader is a separate concept that might not be worth fully explaining, it should probably at least be exposed on the docs site.

[mobsense]

I'm not sure of the general applicability. Are you using it?

[peniqliotuv]

I'm not sure of the general applicability. Are you using it?

Yes

[dev-embedthis]

Want to try your hand at a PR to update the doc?

https://github.com/sensedeep/onedoc

[onhate]

I've developed that, we intentionally left it undocumented at that time for testing but I've been using that for months (if not year) and so far it has proven to work fine, maybe we should document that, would you be willing to help @peniqliotuv ?