Publish stardocs releases when published to BCR.

[cgrindel]

Related Slack thread

📣 rules authors: you can publish stardocs with your releases, and they're nicely rendered at https://registry.bazel.build/docs/your-module
Instructions:
https://github.com/bazelbuild/bazel-central-registry/blob/main/docs/stardoc.md

[cgrindel]

Another Slack post

as a rule author here's how to get your docs to appear:
Make sure you have some native.starlark_doc_extract rules: bazel query 'kind(starlark_doc_extract, //...)'
if you don't, consider switching from load("@bazel_skylib//:bzl_library.bzl", "bzl_library") to load("@bazel_lib//:bzl_library.bzl", "bzl_library") - this also works around bazelbuild/bazel-skylib#568
you can drop anything else related to stardoc from your repo!
As an optimization, use Bazel 7.5.0 or later, so you have bazel query --output_file
add the snippet below to release_prep.sh
Update .bcr/source.template.json to have a docs_url property
Now the BCR UI will find that docs_url and use it to load the stardocs.

# Add generated API docs to the release, see https://github.com/bazelbuild/bazel-central-registry/issues/5593
docs="$(mktemp -d)"; targets="$(mktemp)"
bazel --output_base="$docs" query --output=label --output_file="$targets" 'kind("starlark_doc_extract rule", //...)'
bazel --output_base="$docs" build --target_pattern_file="$targets" --remote_download_regex='.*doc_extract\.binaryproto'
tar --create --auto-compress \
    --directory "$(bazel --output_base="$docs" info bazel-bin)" \
    --file "$GITHUB_WORKSPACE/${ARCHIVE%.tar.gz}.docs.tar.gz" .

See https://github.com/bazel-contrib/yq.bzl/pull/36/files