Update plan

We agreed to publish an updated version of the Scripting API document in March. We need to update https://github.com/w3c/wot/blob/main/charters/wg-2021-extension-plan.md. 

> RESOLUTION: Publish update to Scripting API document (13th of April). Task-force finalizes review 2 weeks before the publication date (27th of March).

*source: https://www.w3.org/2023/02/20-wot-script-minutes.html*