[DURACOM-288] Add dspace.server.ssr.uri in the local.cfg.EXAMPLE

dspace/config/local.cfg.EXAMPLE

@@ -40,6 +40,11 @@ dspace.dir=/dspace
 # It corresponds to the URL that you would type into your browser to access the REST API.
 dspace.server.url = http://localhost:8080/server
 
+# Additional URL of DSpace backend which could be used by DSpace frontend during SSR execution.
+# May require a port number if not using standard ports (80 or 443)
+# DO NOT end it with '/'.
+dspace.server.ssr.url =
+
 # Public URL of DSpace frontend (Angular UI). May require a port number if not using standard ports (80 or 443)
 # DO NOT end it with '/'.
 # This is used by the backend to provide links in emails, RSS feeds, Sitemaps, etc.