Bump docusaurus to v2.0.0-beta.3

[cherewaty]

Motivation

Ran into some problems attempting to customize the webpack config on the alpha version of docusaurus 2.

Approach

Upgrade.

This change introduced stricter use of url-loader, where use of url() in CSS files was breaking. I just slapped a webpack ignore on those for now, since we're exploring changing the CSS build tooling in the coming days.

Learning

https://github.com/facebook/docusaurus/releases/tag/v2.0.0-beta.3

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Latest commit: daf0e1b

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[minkimcello]

I think we need to add some new config to remove the banner?

[cherewaty]

Thanks @minkimcello 🙌 fixed in new commit.

[jorgelainfiesta]

Looking good, thanks Jeffrey!