describe ABORTED as error message for CreateVolumeGroupSnapshot

[nixpanic]

What type of PR is this?

Documentation enhancement for a common CreateVolumeGroupSnapshot error.

What this PR does / why we need it:

The ABORTED error code is currently not documented for CreateVolumeGroupSnapshot but is explained for CreateSnapshot.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce an API-breaking change?:

none

[saad-ali]

Per @bswartz --

• "Not clear what expected behavior if GroupSnapshot for volume A, B, C pending and another one for group B, C, D is triggered"
• "Probably ok if there are 2 overlapping group snapshots and SP decided to return ABORTED for 2nd snapshot and let you retry." So it's probably ok not to explicitly mention this case.

Per @xing-yang: "Specified group snapshot, could mean all parameters have to be the same".

Next step:

• Let's clarify what "specified group snapshot" means.

[saad-ali]

Also, @nixpanic, please make sure you've signed the CLA.

[nixpanic]

Per @bswartz --

* "Not clear what expected behavior if GroupSnapshot for volume A, B, C pending and another one for group B, C, D is triggered"

* "Probably ok if there are 2 overlapping group snapshots and SP decided to return ABORTED for 2nd snapshot and let you retry." So it's probably ok not to explicitly mention this case.

If there is a conflict with the volumes that are part of the group snapshot that should be created, the FAILED_PRECONDITION error is more suitable to return. I do not think ABORTED needs to cover a case like this (too).

Per @xing-yang: "Specified group snapshot, could mean all parameters have to be the same".

Yes, that is more suitable. This ABORTED error is for the CreateVolumeGroupSnapshot call, and is intended to match the similar error that CreateVolume can return.

Next step:

* Let's clarify what "specified group snapshot" means.

I've rephrased specified group snapshot to group snapshot with the exact same parameters and similar.

Also, @nixpanic, please make sure you've signed the CLA.

This was completed with a group approval for IBM employees, sent by Brad Topol in the beginning of the month 🥳