[Modules] Append or subtract elements to current option value

[Xavier D. <xav...@gm...>]

Hello All,

Last feature addition for upcoming v5.3: ability to append or subtract
elements to current option value.

For command-line switches and configuration options whose value is a
colon-separated list, using value prefixed by + or - respectively
append or subtract the value to the existing one.

See details and examples at:
https://modules.readthedocs.io/en/latest/MIGRATING.html#append-or-subtract-elements-to-current-option-value

Regards,
Xavier