fix: invalid note for user that contains an underscore

the mongo db operator replace '_' in the secret name by '-', so do the
same in the NOTES.txt

Author: Romain JACQUET

charts/mongodb-operated/templates/NOTES.txt

@@ -2,5 +2,5 @@
 kubectl get --namespace {{ .Release.Namespace }} -o jsonpath="{.metadata.name}" services {{ .Release.Name }}-mongodb-operated-svc
 2. Get the connection strings for the users defined:
 {{ range .Values.users }}
-    kubectl get secret {{ $.Release.Name }}-mongodb-operated-{{ .db }}-{{ .name }}  -o 'go-template={{ "{{" }} index .data "connectionString.standard" {{ "}}" }}' | base64 -d -w0
+    kubectl get secret {{ $.Release.Name }}-mongodb-operated-{{ .db }}-{{ .name | replace "_" "-" }}  -o 'go-template={{ "{{" }} index .data "connectionString.standard" {{ "}}" }}' | base64 -d -w0
 {{ end }}