Add new Opencontrail repository class

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Change-Id: I72c7c7753f5a21b18bf5f6f1e47c537e554b8d19
Related-PROD: PROD-25035
diff --git a/linux/system/repo/mcp/contrail.yml b/linux/system/repo/mcp/contrail.yml
index 3211f78..b0e9994 100644
--- a/linux/system/repo/mcp/contrail.yml
+++ b/linux/system/repo/mcp/contrail.yml
@@ -1,3 +1,4 @@
+# DEPRECATED since 2018.12+ release.
 parameters:
   _param:
     linux_repo_contrail_component: oc311