Generate subcommand is unable to add multiple capabilities to config with single flag

[tswift242]

The description for the capability related flags for the generate subcommand made it seem like that I could add or remove multiple capabilities with one flag. For example, the description for --process-cap-add-ambient is just "Add Linux ambient capabilities". I've tried many varieties of --process-cap-add-ambient '["CAP_AUDIT_WRITE", "CAP_CHOWN", ...]' but none seem to work. They only way it seems to work is by specifying the flag each time for each capability, which leads to a very verbose shell command.

If multiple capabilities per flag is not supported, that would be a nice enhancement. If it is supported, having a doc example for this would help.

It would also help to have a top level --process-cap-add convenience flag for adding a capability to all 5 capability sets.

[zhouhao3]

I fixed this problem in #674 and added --process-cap-add option in #675.