Merge branch 'stable-3.0' into stable-3.1
* stable-3.0:
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: I6b3a55980924ca8f89013db1474fb1b5f15c5bda