Reorder the state selection caveats doc to emphasise common false positives

[joellabes]

Contributions

• I have read the contribution docs, and understand what's expected of me.

Link to the page on docs.getdbt.com requiring updates

From discussion in Slack

The false positives section is the most relevant and important way that people get into trouble with state selection, but it's somewhat de-emphasised.

What part(s) of the page would you like to see updated?

Let's bring it up to the top - the slack thread calls for a ⚠️ and a box around it which is probably overkill, but a bit more emphasis through more worked examples etc

Additional information

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