Update silviculture example vignette (future task)

The RESULTS database for bcgov Silviculture data is being modernized to SILVA, see https://bcgov.github.io/forestry-digital-services/applications/results.html

The resulting table snapshots in the B.C. Data Catalogue will likely change in design/names/records. We should watch for changes and either update [the vignette](https://bcgov.github.io/bcdata/articles/explore-silviculture-data-using-bcdata.html#reforestation-with-climate-considerations) (or deprecate).

'cc @hgriesbauer