docs: Increase content width

[duncandewhurst]

Related issues

• [Docs update] Fix codelists horizontal & vertical scroll, check hyperlinks #161

Description

• Wrap each codelist table inside a collapsible drop-down.
• Collapse dropdowns for codelists with more the ten codes.
• Make main content wider
• Consistently use - as separator in codes for classification_scheme.csv to allow for text wrapping

With these changes, only location_gazetteers is displayed with a horizontal scroll at standard 1920x1080 screen resolution.

Merge checklist

• Update the changelog (style guide)
• Run ./manage.py pre-commit

If you added or removed a field:

• Update the collapse option of the jsonschema directives for dataset, resource, hazard, exposure, vulnerability and loss on reference/schema.md

Having trouble?

See how to resolve check failures.

[duncandewhurst]

I don't think this PR requires a changelog entry.

[duncandewhurst]

Moving back to draft to address other CSS related requests in #161 (comment)