Find a better example and update 'accordion with summary line'

[calvin-lau-sig7]

Context

The new accordion component in v4.0.0 includes new accessibility guidance to avoid using summary lines, and if so to keep them as short as possible.

The example for summary line does not fully match with the guidance.

It'd be ideal to find or encourage an live website or service that uses an accordion with summary line to follow the guidance so we can hold it up as an example.

Done when:

• Find website or service using accordion with summary line
• Get in touch with team managing the accordion
• Match their accordion and Design System guidance
• Update example in accordion component