python: publish sphinx docs to googleapis.dev
**Background:**
This is a follow-up to the PR that adds sphinx docs.
Googleapis.dev hosts client library documentation for several languages as
well as documentation for core packages such as google-api-core. It is owned
and maintained by the Cloud DevRel Core team.
**About this change:**
The `kokoro/docs/publish-python.sh` script builds the docs with sphinx, then
uses the [googleapis/docuploader](https://github.com/googleapis/docuploader)
tool to publish to googleapis.dev. The publish script is triggered manually
with a Kokoro RELEASE type job. Googlers, see go link
protobuf-docs-python-design for additional internal references.
diff --git a/kokoro/docs/publish-python.sh b/kokoro/docs/publish-python.sh
new file mode 100755
index 0000000..eea1755
--- /dev/null
+++ b/kokoro/docs/publish-python.sh
@@ -0,0 +1,51 @@
+#!/bin/bash
+# Adapted from https://github.com/googleapis/google-cloud-python/blob/master/.kokoro/publish-docs.sh
+
+set -eo pipefail
+
+# Disable buffering, so that the logs stream through.
+export PYTHONUNBUFFERED=1
+
+cd github/protobuf/python
+
+# install package
+sudo apt-get update
+sudo apt-get -y install software-properties-common
+sudo add-apt-repository universe
+sudo apt-get update
+sudo apt-get -y install unzip
+wget https://github.com/protocolbuffers/protobuf/releases/download/v3.11.2/protoc-3.11.2-linux-x86_64.zip
+unzip protoc-3.11.2-linux-x86_64.zip bin/protoc
+mv bin/protoc ../src/protoc
+python3.6 -m venv venv
+source venv/bin/activate
+python setup.py install
+
+# install docs dependencies
+python -m pip install -r docs/requirements.txt
+
+# build docs
+cd docs
+make html
+cd ..
+deactivate
+
+python3.6 -m pip install protobuf==3.11.1 gcp-docuploader
+
+# install a json parser
+sudo apt-get -y install jq
+
+# create metadata
+python3.6 -m docuploader create-metadata \
+ --name=$(jq --raw-output '.name // empty' .repo-metadata.json) \
+ --version=$(python3 setup.py --version) \
+ --language=$(jq --raw-output '.language // empty' .repo-metadata.json) \
+ --distribution-name=$(python3 setup.py --name) \
+ --product-page=$(jq --raw-output '.product_documentation // empty' .repo-metadata.json) \
+ --github-repository=$(jq --raw-output '.repo // empty' .repo-metadata.json) \
+ --issue-tracker=$(jq --raw-output '.issue_tracker // empty' .repo-metadata.json)
+
+cat docs.metadata
+
+# upload docs
+python3.6 -m docuploader upload docs/_build/html --metadata-file docs.metadata --staging-bucket docs-staging
