Add `terminate_delay` and `fork_delay` parameters to `keepalived::vrrp::track_process`

[trefzer]

These seem to be available from keepalived 2.0.16 onwards. Which also changes purpose of the delay parameter to be the default for both.

[smortex]

REFERENCE.md is outdated

Please update REFERENCE.md with

$ bundle exec rake strings:generate:reference

Add it to the PR and CI should continue.