Correct decimation plugin documentation (#8801)

* Correct decimation plugin documentation

* The default for decimation is `false`.
* Added a sample for data decimation
* Corrected an issue in the decimation plugin when switched from enabled to disabled

docs/scripts/utils.js

@@ -155,3 +155,7 @@ export function newDate(days) {
 export function newDateString(days) {
   return DateTime.now().plus({days}).toISO();
 }
+
+export function parseISODate(str) {
+  return DateTime.fromISO(str);
+}