Feature/add container refs

[kindoflew]

Why

Resolves #1770.

What

Added the DOM refs for the outer and inner div containers -- container and content respectively (as they were named pre-9.x.x). Also, updated docs and README to reflect changes.

Checklist

• Documentation updated
• Ready to be merged

For the docs, I updated the organization a little bit and made a "ref Properties" section that includes these two refs, as well as the scrollTo method. It just seemed to stand out a little bit more, as opposed to a list (although, I suppose it could also be a table 🤔 ).

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[joshuaellis]

Just pointing this at release/9.4.0

I will release this on beta tonight, cc @pvldsgn

[sampashas]

I look forward, thank you @joshuaellis, @kindoflew