Fix typos

management/templates/system-backup.html

@@ -361,7 +361,7 @@ function init_inputs(target_type) {
 }
 
 // Return a two-element array of the substring preceding and the substring following
-// the first occurence of separator in string. Return [undefined, string] if the
+// the first occurrence of separator in string. Return [undefined, string] if the
 // separator does not appear in string.
 const split1_rest = (string, separator) => {
     const index = string.indexOf(separator);