cmd ref: describe `update available` output (for import stages) in `status`

[efiop]

Related #474

UPDATE: Jump to #477 (comment) for some more details.

[dnabanita7]

Can I take up the issue?

[shcheklein]

it depends on #185 , there is a PR #416 by @sanidhyamangal that still requires more work.

[jorgeorpinel]

Not sure what this one means. @efiop ? Thanks

[shcheklein]

Probably for the imported stages dvc status can show the update available if running the dvc update would move it to the new version.