Update rules for 1860 and 18Ireland to deprecate my personal dropbox

[benjaminxscott]

Before clicking "Create"

• [x] Branch is derived from the latest master
• [NA] Add the pins or archive_alpha_games label if this change will break existing games
• [ ] Code passes linter with docker compose exec rack rubocop -a
• [ ] Tests pass cleanly with docker compose exec rack rake

Implementation Notes

Explanation of Change

Update direct rules links for 1860 and 18Ireland to point to BGG instead of my personal dropbox (reduce bus factor and fragility)

Screenshots

Any Assumptions / Hacks