Link from Core capability headings to capability index

[davidstanke]

#691 adds headers to the capability index consistent with Core V2. In the popovers which correspond to the capability headings ("Climate for Learning" etc.), add links to the corresponding headers on the capability index page (e.g. /capabilities/#climate+for+learning)

The links can be added to this source file: https://github.com/dora-team/dora.dev/blob/main/svelte/core-v2/src/lib/core_data.json