message: build: correct typo in OS X instructions
  Added missing quotes and clarified the syntax of the .bazelrc file
diff: @@ -56,14 +56,15 @@ Envoy compiles and passes tests with the version of clang installed by XCode 9.3
  Apple LLVM version 9.1.0 (clang-902.0.30).
  In order for bazel to be aware of the tools installed by brew, the PATH
  -variable must be set for bazel builds. This can be accomplished setting
  +variable must be set for bazel builds. This can be accomplished by setting
  +this in your `$HOME/.bazelrc` file:
  ```
  ---action_env=PATH=/usr/local/bin:/opt/local/bin:/usr/bin:/bin"
  +build --action_env=PATH="/usr/local/bin:/opt/local/bin:/usr/bin:/bin"
  ```
  -either on the command line when running `bazel build`/`bazel test` or
  -in your `$HOME/.bazelrc` file.
  +Alternatively, you can pass `--action_env` on the command line when running
  +`bazel build`/`bazel test`.
  3. Install Golang on your machine. This is required as part of building [BoringSSL](https://boringssl.googlesource.com/boringssl/+/HEAD/BUILDING.md)
  and also for [Buildifer](https://github.com/bazelbuild/buildtools) which is used for formatting bazel BUILD files.
  