This is determined by looking at the `pdk` key in the config. If `pdk` doesn't exist, `id` will be used (assuming that the structure of the shuttle ID follows ttX where X=[sky, ihp, gf]). If any part fails, it will fall back to `openframe_sky130`.
The pinout can also be manually controlled by setting the `datasheet_config.pinout` key in the shuttle config, and that will be used verbatim. Note that `datasheet_config.pinout` is not checked, so it *must* be exact, otherwise it will cause the datasheet build to fail.
Switching from `gfm` to `markdown` should enable more formatting options. The extensions have been configured to be similar to `gfm` but provide some additional things, like `line_blocks` and `lists_without_preceding_blankline`s.