Add version conditional for replication-command.md (#59524)

Co-authored-by: mc <42146119+mchammer01@users.noreply.github.com>

Author: khanhgee

data/reusables/enterprise_installation/replication-command.md

@@ -4,6 +4,16 @@
    ghe-repl-start
    ```
 
+   {% ifversion ghes < 3.19 %}
    > [!WARNING]
    > `ghe-repl-start` causes a brief outage on the primary server, during which users may see internal server errors. To provide a friendlier message, run `ghe-maintenance -s` on the primary node before running `ghe-repl-start` on the replica node to put the appliance in maintenance mode. Once replication starts, disable maintenance mode with `ghe-maintenance -u`. Git replication will not progress while the primary node is in maintenance mode.
    > If you are running version 3.14.20, 3.15.15, 3.16.11, 3.17.8, 3.18.2, or a later version including future releases like 3.19, you no longer need to put the primary in maintenance mode prior to running `ghe-repl-start`. This command is no longer expected to cause an outage on the primary server. However, when setting up a new replica, `ghe-repl-start` won't cause an outage as long as you run `ghe-config-apply` between `ghe-repl-setup` and `ghe-repl-start`. Skipping `ghe-config-apply` and going straight from `ghe-repl-setup` to `ghe-repl-start` will still result in an outage.
+
+   {% else %}
+   > [!WARNING]
+
+   > [!WARNING]
+   > To ensure uninterrupted service when setting up a new replica, run `ghe-config-apply` between `ghe-repl-setup` and `ghe-repl-start`. This allows the primary server to remain available throughout the replication setup process.
+
+
+   {% endif %}