Missing links for JSON filter and sum numbers

Hi team,

I found multiple pages are missing links for

Writing an aggregate to sum numbers
Writing a JSON filter

Pages:

https://www.fluvio.io/docs/smartmodules/features/operators/array-map#read-next

https://www.fluvio.io/docs/smartmodules/features/operators/filter-map#read-next

Another one:

The [car-count example in GitHub](https://github.com/infinyon/stateful-dataflows-examples/blob/main/dataflows-inline/car-processing) from https://www.fluvio.io/sdf/latest/concepts/operators#assign-key.