Fix missing Managers route on serviceRoot

Managers routing was missing on serviceroot.  This resolves it.

Tested By:
Pulled ServiceRoot, and observed endpoint exists

Change-Id: Id2ef8e0107512ee231ec0af9514f26526cb30c73
Signed-off-by: Ed Tanous <ed.tanous@intel.com>
diff --git a/redfish-core/lib/service_root.hpp b/redfish-core/lib/service_root.hpp
index 296ad92..cbe3f11 100644
--- a/redfish-core/lib/service_root.hpp
+++ b/redfish-core/lib/service_root.hpp
@@ -54,6 +54,7 @@
         res.jsonValue["Chassis"] = {{"@odata.id", "/redfish/v1/Chassis"}};
         res.jsonValue["JsonSchemas"] = {
             {"@odata.id", "/redfish/v1/JsonSchemas"}};
+        res.jsonValue["Managers"] = {{"@odata.id", "/redfish/v1/Managers"}};
         res.jsonValue["SessionService"] = {
             {"@odata.id", "/redfish/v1/UpdateService"}};
         res.jsonValue["Systems"] = {{"@odata.id", "/redfish/v1/Systems"}};