Update attachment link accessibility guidance

[jon-kirwan]

What

Update attachment link accessibility guidance

Why

See https://www.w3.org/WAI/WCAG22/Understanding/target-size-minimum.html. The Attachment link component might fail 2.5.8 Target Size (Minimum) if not used in the correct way. The last two examples (with target blank
and with data attributes) show the component used without a containing element such as a paragraph tag or a list item element and the target height is only 20px high (24px is required for the success criterion).

This should be highlighted in the guidance.

Anything else

I explored a few other approaches here.

• enable the Axe target-size rule, which is not enabled by default. Unfortunately, this doesn’t get flagged as a violation (because there are no intersecting elements in the examples).
• embedding the final two examples within Govspeak or a paragraph element. However, I find this potentially confusing, as both examples demonstrate usage with data attributes or the target="_blank" attribute. Including extra elements might mislead users into thinking these are necessary for the component to work. Additionally, the component can be implemented in various ways that would still meet the success criteria, such as within a list item.