Replaced smart quotes with plain quotes.
Replaced smart quotes with plain quotes.

Also added missing blank line before code region to fix Dockerfile formatting on
the web site.

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Reviewed-on: https://github.com/bazelbuild/bazel/pull/570
MOS_MIGRATED_REVID=107470895

davidzchen/bazel-website,bazelbuild/bazel-website,davidzchen/bazel-website,bazelbuild/bazel-website,bazelbuild/bazel-website,davidzchen/bazel-website,davidzchen/bazel-website