Clarify pollingInterval and Caching Metrics

[rickbrouwer]

I think the documentation on pollingInterval could be improved. Described: “This is the interval to check each trigger on. By default, KEDA will check each trigger source on every ScaledObject every 30 seconds.” However, pollingInterval is only relevant from 0<->1 scaling.
The Datadog scaler documentation describes better how pollingInterval works. I would like to clarify the text for pollingInterval. I would also like to add a line with a reference to ‘Caching Metrics’ so if you want to respect the pollingInterval to the external metric for 1 <-> N scaling.

In the text about Caching Metrics I would like to add a reference to the triggers. This because ‘caching metrics’ give information about ‘This feature enables’, but the not which one.

I think that with these updates the documentation and clarity on pollingInterval and Caching Metrics will be improved.

Use-Case

Clarify pollingInterval and Caching Metrics