add the new backend domain to the proxy list (#1844)

Author: arikalon1

docs/setup-robusta/proxies.rst

@@ -34,7 +34,7 @@ If you are using Robusta SaaS, ensure that your network allows access to the fol
 
 .. code:: bash
 
-    api.robusta.dev,robusta-charts.storage.googleapis.com,us-central1-docker.pkg.dev,platform.robusta.dev,xvyhpoxfmtpuqqeyqkso.supabase.co,relay.robusta.dev
+    api.robusta.dev,robusta-charts.storage.googleapis.com,us-central1-docker.pkg.dev,platform.robusta.dev,xvyhpoxfmtpuqqeyqkso.supabase.co,relay.robusta.dev,sp.robusta.dev
 
 Running Robusta in Air-Gapped or Offline Environments
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