Merge branch 'stable-2.16' into stable-3.0 * stable-2.16: Bump Bazel version to 2.2.0 Bump required Bazel version to 2.1.0 Upgrade bazlets to latest stable-2.16 to build with 2.16.16 API Documentation: Refactor to match other plugin documentation Add an empty tools/BUILD file explicitly for Bazel Upgrade bazlets to latest stable-2.16 Upgrade bazlets to latest stable-2.16 Upgrade bazlets to latest stable-2.15 Upgrade bazlets to latest stable-2.14 config.md: Correct formatting of config values Change-Id: I8cc6f59eaf1bc33b9d37b7ec56c74181d9aff4f3