docs(galaxy): rewrite stale PR-4.W/legacy-host forward-ref comments to shipped reality (#13)

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy/GalaxyDriverFactoryExtensions.cs

@@ -14,10 +14,9 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy;
 ///     <see cref="DriverTypeName"/> into live <see cref="GalaxyDriver"/> instances.
 /// </summary>
 /// <remarks>
-///     The driver-type name <c>"GalaxyMxGateway"</c> is intentionally distinct from the
-///     legacy proxy's <c>"Galaxy"</c> so both factories can be registered simultaneously
-///     during parity testing (Phase 5). PR 4.W will add a server-side <c>Galaxy:Backend</c>
-///     switch that materialises a Galaxy DriverInstance under one or the other type name.
+///     <c>"GalaxyMxGateway"</c> is the sole Galaxy driver-type name. The legacy
+///     <c>"Galaxy"</c> proxy type (retired in PR 7.2) no longer exists; there is no
+///     server-side backend switch — every Galaxy DriverInstance row uses this type name.
 /// </remarks>
 public static class GalaxyDriverFactoryExtensions
 {