docs: update docstrings (via synth)

[yoshi-automation]

This PR was generated using Autosynth. 🌈

Log from Synthtool

2020-04-21 06:36:12,424 synthtool > Executing /tmpfs/src/git/autosynth/working_repo/synth.py.
On branch autosynth
nothing to commit, working tree clean
2020-04-21 06:36:12,487 synthtool > Ensuring dependencies.
2020-04-21 06:36:12,815 synthtool > Cloning googleapis.
2020-04-21 06:36:13,147 synthtool > Generating code for: //google/cloud/webrisk/v1beta1:webrisk-v1beta1-py.
2020-04-21 06:36:16,166 synthtool > Generated code into /tmpfs/tmp/tmp16gad0j7.
2020-04-21 06:36:16,191 synthtool > Generating code for: //google/cloud/webrisk/v1:webrisk-v1-py.
2020-04-21 06:36:19,298 synthtool > Generated code into /tmpfs/tmp/tmpzetpp00a.
2020-04-21 06:36:19,314 synthtool > Replaced '\'__doc__\': """Attributes:' in google/cloud/webrisk_v1/proto/webrisk_pb2.py.
2020-04-21 06:36:19,315 synthtool > Replaced '\'__doc__\': """Attributes:' in google/cloud/webrisk_v1beta1/proto/webrisk_pb2.py.
.coveragerc
.flake8
.github/CONTRIBUTING.md
.github/ISSUE_TEMPLATE/bug_report.md
.github/ISSUE_TEMPLATE/feature_request.md
.github/ISSUE_TEMPLATE/support_request.md
.github/PULL_REQUEST_TEMPLATE.md
.github/release-please.yml
.gitignore
.kokoro/build.sh
.kokoro/continuous/common.cfg
.kokoro/continuous/continuous.cfg
.kokoro/docs/common.cfg
.kokoro/docs/docs.cfg
.kokoro/presubmit/common.cfg
.kokoro/presubmit/presubmit.cfg
.kokoro/publish-docs.sh
.kokoro/release.sh
.kokoro/release/common.cfg
.kokoro/release/release.cfg
.kokoro/trampoline.sh
CODE_OF_CONDUCT.md
CONTRIBUTING.rst
LICENSE
MANIFEST.in
docs/_static/custom.css
docs/_templates/layout.html
docs/conf.py.j2
noxfile.py.j2
renovate.json
setup.cfg
Running session blacken
Creating virtual environment (virtualenv) using python3.6 in .nox/blacken
pip install black==19.3b0
black docs google tests noxfile.py setup.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/__init__.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/__init__.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk_v1/__init__.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk_v1/gapic/enums.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk_v1/gapic/transports/web_risk_service_grpc_transport.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk_v1/gapic/web_risk_service_client_config.py
reformatted /tmpfs/src/git/autosynth/working_repo/docs/conf.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk_v1/types.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk_v1beta1/__init__.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk_v1beta1/gapic/enums.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk_v1/proto/webrisk_pb2_grpc.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk_v1beta1/gapic/transports/web_risk_service_v1_beta1_grpc_transport.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk_v1beta1/gapic/web_risk_service_v1_beta1_client_config.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk_v1/gapic/web_risk_service_client.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk_v1beta1/proto/webrisk_pb2_grpc.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk_v1beta1/gapic/web_risk_service_v1_beta1_client.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk_v1beta1/types.py
reformatted /tmpfs/src/git/autosynth/working_repo/noxfile.py
reformatted /tmpfs/src/git/autosynth/working_repo/tests/unit/gapic/v1/test_web_risk_service_client_v1.py
reformatted /tmpfs/src/git/autosynth/working_repo/tests/unit/gapic/v1beta1/test_web_risk_service_v1_beta1_client_v1beta1.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk_v1/proto/webrisk_pb2.py
reformatted /tmpfs/src/git/autosynth/working_repo/google/cloud/webrisk_v1beta1/proto/webrisk_pb2.py
All done! ✨ 🍰 ✨
23 files reformatted, 7 files left unchanged.
Session blacken was successful.
2020-04-21 06:36:23,647 synthtool > Wrote metadata to synth.metadata.