[Doc] update setup topic

[jcalcaben]

Description

This PR updates the Venia setup topic content to remove the recommendation for a hard coded Magento version. Readers are now directed to the compatibility table.

Related Issue

Closes #ISSUE_NUMBER.

Acceptance

@ericerway

Verification Stakeholders

@ericerway

Specification

Verification Steps

1. Go to the FOO page.
2. Verify the BAR shows up.
3. Make sure BAZ does a thing.

Screenshots / Screen Captures (if appropriate)

Checklist

• I have updated the documentation accordingly, if necessary.
• I have added tests to cover my changes, if necessary.

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