DOCS: Additional examples of non-exportable objects

I try to keep track of non-exportable object examples in the [Non-Exportable Objects](https://cran.r-project.org/web/packages/future/vignettes/future-4-non-exportable-objects.html) vignette. Let's use this issue to gather additional examples of packages and object classes that cannot be exported to another R process or saved to be used in another R session.

Additional examples:

* [x] Package **raster**, e.g. `raster::writeStart()` (https://stackoverflow.com/questions/65148384)
* [x] Package **xboost**, e.g. `xgboost::xgb.DMatrix()` (https://stackoverflow.com/questions/65136945/issues-with-running-xgboost-in-multiple-r-processes)
* [x] Package **terra**, e.g. `SpatRaster` and `SpatVector` (https://stackoverflow.com/questions/67445883/terra-package-returns-error-when-try-to-run-parallel-operations). Mention also `terra::wrap()` for "marshalling"
* [x] Bioconductor package **ShortRead**, e.g. 'FastqStreamerList' (https://support.bioconductor.org/p/9135851/)