Since the workflow relies on the build-docs target existing in the
Makefile to ensure we don't commit a change without calling it, and
since we removed it in the previous commit to fold it in generate, we
don't need it anymore so we can remove it.

Since the `make generate' call is already required if modifying the
docs, and we check that during validate, this is safe to remove.

Since we have merged `build-docs' with `generate', we don't need to
manually invoke `packer-sdc renderdocs' before the old build-docs.

When the docs were modified last, the web-docs weren't updated, and the
action did not trigger on that branch, leading to the pipelines failing
after that, so we fix this issue now.

The docs.zip file should not be part of the release as it is no longer
generated nor required to build the docs for a plugin.

Keeping this in the releaser config caused the release to fail before
the artifacts were updated, leading to a corrupted release.