Adding documentation for building from current master without cloning.

[devin-petersohn]

It might be useful for downstream projects to build from the current master without having to clone. This additional doc explains how.

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Merged build finished. Test PASSed.

[AmplabJenkins]

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[robertnishihara]

The documentation looks good to me.

Do you find it useful to do this? In the past I feel like I've seen pip install hang when trying to install from GitHub (or error messages would be suppressed if you don't have some dependency like cmake installed or things like that).

Maybe add a note indicating that this approach may be less reliable? If you think it's reliable enough then no need to.

[robertnishihara]

Note that I just ran this on my mac and it worked fine (though it took a little while). However, I already have all of the relevant dependencies installed and I'm not sure about the behavior when you don't have them installed.

[devin-petersohn]

It does give you the error when it fails. I have had a couple of people try it without having the brew dependencies, and it gives you the failure stack. We could add a note saying that it still requires the dependencies above.

I don't think it takes any longer than building from source normally does, this is just nicer for building downstream apps.

[robertnishihara]

Ok then I think it's good as is, thanks!

[robertnishihara]

Went ahead and merged it. Since it only changes the documentation, it's probably enough for the linting to pass (the linting tries to build the documentation).