Fix double spaced sentences

doc/administration/geo/replication/configuration.md

doc/administration/geo/replication/faq.md

doc/administration/gitaly/praefect.md

doc/administration/operations/moving_repositories.md

doc/administration/operations/unicorn.md

...dministration/troubleshooting/gitlab_rails_cheat_sheet.md

doc/administration/troubleshooting/linux_cheat_sheet.md

doc/development/adding_database_indexes.md

doc/development/code_review.md

doc/development/contributing/index.md

doc/development/elasticsearch.md

doc/development/fe_guide/performance.md

doc/development/github_importer.md

doc/development/go_guide/index.md

doc/development/logging.md

doc/development/migration_style_guide.md

doc/development/namespaces_storage_statistics.md

doc/development/pry_debugging.md

doc/development/reactive_caching.md

doc/development/renaming_features.md