[chronik.e.cash] Fix internal links relative paths

Summary: This diff fixes the relative paths of links in chronik.e.cash.

Test Plan:
npm run build in web/chronik.e.cashnpm start
Test the links

Reviewers: Fabien, #bitcoin_abc

Reviewed By: Fabien, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D18516