Fix learn more for Onion-Location
Similar to legacy/trac#34369 (moved), we have to fix the learn more links in the doorhanger and in about:preferences to point to https://tb-manual.torproject.org/[locale]/onion-services/
Similar to legacy/trac#34369 (moved), we have to fix the learn more links in the doorhanger and in about:preferences to point to https://tb-manual.torproject.org/[locale]/onion-services/