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: Remove bazel issue
Documentation: Refactor to match other plugin documentation
Documentation: Add missing alternative for plugin in-tree testing
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
Change-Id: I1458812b7f22229d4dbd2a699d156176a9230fc8