[chronik.e.cash] Update chronik-client in docs
Summary: Update docs page to always use the latest version of chronik-client
Test Plan: docker build -f chronik.e.cash.Dockerfile -t chronik-docs .
Reviewers: #bitcoin_abc, emack
Reviewed By: #bitcoin_abc, emack
Subscribers: emack
Differential Revision: https://reviews.bitcoinabc.org/D16750