docs(istio-csr): add documentation for podDisruptionBudget configuration to provide users with guidance on setting disruption budgets

Signed-off-by: frauniki <[email protected]>

Author: frauniki

deploy/charts/istio-csr/README.md

@@ -607,5 +607,12 @@ extraObjects:
     metadata:
       name: '{{ template "cert-manager-istio-csr.fullname" . }}-extra-configmap'
 ```
+#### **podDisruptionBudget** ~ `object`
+> Default value:
+> ```yaml
+> {}
+> ```
+
+Configures a disruption budget for istio-csr.
 
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