add submodule update command to README for Building Raven

[ddouglas]

[linux-foundation-easycla[bot]]

• :white_check_mark:login: ddouglas / (36a85c826b223c89e51f0411439d15026186020f)

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[yaash45]

Hi @ddouglas! Not sure if you had a chance to see the discussion on #66, but it looks like we both have PRs to address the same issue.

I opted to supplement the introduction with a sentence indicating that a --recursive clone was necessary to build this project. I considered this sufficient for this use case.

However, after reviewing your PR, I see the merit in adding the command to update submodules to the build steps like you did. This way, the user is building with the correct, initialized submodules each time.

Let me know your thoughts, but I am leaning towards accepting your changes and closing my PR (#66). Thanks!

[jminor]

This PR was folded into #66 - thanks to you both for making Raven's build instructions better :)