pod: Add important comment for Cmd type

[jodh-intel]

The Cmd type encodes the user and group details that the workload will be run as.

It currently encodes those values as strings, although since the OCI spec and the Kata gRPC protocol encode such values as integers, we would ideally like to change Cmd so that the user and group details are also encoded as integer values (with a conversion to strings for sending such details to hyperstart which uses string types for them).

Add a comment explaining why we cannot change the type of the user and group fields to an integer type.

Fixes #533.

Signed-off-by: James O. D. Hunt james.o.hunt@intel.com

[jodh-intel]

A few more details here:

• https://github.com/jodh-intel/virtcontainers/commit/a8e6aff149a2f0db033ca8ee07cc8eb0c58bc41c

[devimc]

lgtm

[sboeuf]

LGTM