Update metadata docs for "libraries" and "compilationSettings" fields

[kuzdogan]

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[cameel]

Thanks! Looks good, but there's actually even more we could add. See my suggestions below.

[kuzdogan]

Rebased and updated. Now the settings only has "compilationTarget" and "libraries", and refers the rest to the std-json docs.

[cameel]

Still needs some corrections.

[cameel]

The PR looks good now. Thanks for taking the time to improve this part of the docs :)

[cameel]

Oh, one more thing before we merge. Can you squash the commits a bit? Does not have to be one, but we generally at least squash the fixes from review into the original commits to keep history easier to understand.

[kuzdogan]

Rebased