Fix external links in development docs

doc/development/code_review.md

doc/development/contributing/design.md

doc/development/contributing/merge_request_workflow.md

doc/development/documentation/site_architecture/index.md

doc/development/documentation/styleguide/index.md

doc/development/documentation/testing.md

doc/development/i18n/externalization.md

doc/development/service_ping/troubleshooting.md

doc/development/snowplow/troubleshooting.md