1. Add new pattern `runtime/doc/**`. This is a common case were the
contributor modifies only the help file but the doc gen would discard
their changes.
2. Add to the output what the changes after running doc gen would be.
[skip ci]
Repurpose the api-docs workflow to also run in all PR's but work only as
a check, if the changes in the PR introduce doc changes that are not
committed fail.
[skip ci]