docs: CURRENT_STATE still reports 0.4.2 as in progress after it shipped #136

CURRENT_STATE.md describes the v0.4.x line as still in flight. All of it has
shipped.

Stale statements

• Current Version says 0.4.1 and "A 0.4.2 patch is in progress
  (STATUS_TRANSITION_VIOLATION per-connector fix, bug: STATUS_TRANSITION_VIOLATION false positives: connector status is tracked globally, not per connector #128)".
  @ocpp-debugkit/toolkit@0.4.2 is published and holds the latest dist-tag,
  the v0.4.2 tag exists, and bug: STATUS_TRANSITION_VIOLATION false positives: connector status is tracked globally, not per connector #128 is closed.
• Active Milestone says the two false-positive bugs "are being fixed" and
  places bug: STATUS_TRANSITION_VIOLATION false positives: connector status is tracked globally, not per connector #128 "in 0.4.2". Both METER_VALUE_ANOMALY false positives: monotonicity is checked across all measurands at once #127 and bug: STATUS_TRANSITION_VIOLATION false positives: connector status is tracked globally, not per connector #128 are closed and released.
• What's Next item 1 says to "cut and publish v0.4.0". v0.4.0, v0.4.1 and
  v0.4.2 have all been published.
• What's Done carries release sections through v0.3.1 and has no record of
  the v0.4.x releases at all.

Fix

Move Current Version to 0.4.2, restate the milestone as v0.4.x complete with
v0.5.0 (OCPP 2.0.1) next, add a v0.4.x release section to What's Done, and drop
the stale first item from What's Next.

Documentation only. No changeset: CURRENT_STATE.md is not in the package
files list, so it does not ship to npm.

Landing in #135, which already edits this file and is not yet merged, rather
than as a second branch touching the same regions.