Added teh custom_ca option to the example

content/rke/latest/en/etcd-snapshots/recurring-snapshots/_index.md

@@ -89,6 +89,10 @@ services:
         region: ""
         folder: "" # Optional - Available as of v0.3.0
         endpoint: s3.amazonaws.com
+        custom_ca: |-
+          -----BEGIN CERTIFICATE-----
+          $CERTIFICATE
+          -----END CERTIFICATE-----
 ```
 
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