[accessibility] The list marker links should be conveyed as buttons

[Malvoz]

The list-markers-li list items contain <a href="#"> elements, I suggest setting the role="button" attribute (similar to Leaflet's zoom controls, for example) such that they're conveyed as buttons and not regular links to screen reader users.

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Other resources that may be helpful:

• Leaflet guide to accessibility: Test your maps
• Leaflet Plugin Authoring Guide: Content Accessibility