[chronik.e.cash] enable trailing slashes for consistent URL structure

Summary:
Due to nginx redirects, URLs without the "/" suffix will lose "docs" in the domain. If we can use trailingSlash to keep in-page routes
ending with slashes, it would largely solve the redirection issues caused by copying and pasting links and refreshing.

Test Plan: Rebuilt the chronik.e.cash documentation in a new environment to test trailingSlash

Reviewers: emack, Fabien, O1 Bitcoin ABC, #bitcoin_abc

Reviewed By: emack, Fabien, O1 Bitcoin ABC, #bitcoin_abc

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D17884