Fix capitalization in geo and HA docs

doc/administration/geo/disaster_recovery/index.md

doc/administration/geo/replication/configuration.md

doc/administration/geo/replication/database.md

doc/administration/geo/replication/faq.md

doc/administration/geo/replication/high_availability.md

doc/administration/geo/replication/index.md

doc/administration/geo/replication/security_review.md

doc/administration/geo/replication/troubleshooting.md

doc/administration/geo/replication/using_a_geo_server.md

doc/administration/high_availability/README.md

doc/administration/high_availability/consul.md

doc/administration/high_availability/database.md

doc/administration/high_availability/gitlab.md

doc/administration/high_availability/load_balancer.md

doc/administration/high_availability/nfs.md

...administration/high_availability/nfs_host_client_setup.md

doc/administration/high_availability/pgbouncer.md

doc/administration/high_availability/redis.md

doc/administration/high_availability/redis_source.md