[IMP] developer/reference/cli: --db_replica_(host|port)

The option was introduced last year but the documentation hasn't been
updated accordingly.

Co-authored-by: Julien Castiaux <[email protected]>

Author: fja-odoo

content/developer/reference/cli.rst

@@ -221,6 +221,20 @@ Database
 
     port the database listens on, defaults to 5432
 
+.. option:: --db_replica_host <hostname>
+
+    host for the replica server
+
+    When set, it redirect all read-only transactions to this host, instead of of the primary
+    database at ``--db_host``.
+
+    The host can be set to an empty string or to the same value as ``--db_host`` to simulate a
+    replicated environnement, for development.
+
+.. option:: --db_replica_port <port>
+
+    port the replica database listens on, defaults to 5432
+
 .. option:: --db-filter <filter>
 
     hides databases that do not match ``<filter>``. The filter is a