Add a blog post about docker_build
Add a blog post about docker_build

Also update the Docker section of the FAQ.

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MOS_MIGRATED_REVID=99206773

laszlocsomor/bazel-blog,bazelbuild/bazel-blog,davidzchen/bazel-blog,bazelbuild/bazel-blog,laszlocsomor/bazel-blog,laszlocsomor/bazel-blog,laszlocsomor/bazel-blog,davidzchen/bazel-blog,bazelbuild/bazel-blog,davidzchen/bazel-blog,davidzchen/bazel-blog