Allow configuration of vrouter vr_flow_entries param

To set up custom vrouter flow table size param vr_flow_entries
should be configurable via salt formulas.

PROD-34548

Change-Id: Ibc2c73e2af0d78c175c41f3df52edcdc197856b3
(cherry picked from commit 3c41c6cc45aa9cb35f4507f7c0fb810ae04f66c6)
diff --git a/README.rst b/README.rst
index 72b138a..f76e64f 100644
--- a/README.rst
+++ b/README.rst
@@ -613,6 +613,7 @@
         enabled: True
         hostname: node-12.domain.tld
         flow_hold_limit: 0
+        vr_flow_entries: 2097152
         discovery:
           host: 127.0.0.1
         interface: