Missing links for JSON filter and sum numbers

[tz-torchai]

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 from https://www.fluvio.io/sdf/latest/concepts/operators#assign-key.

[ajhunyady]

@tz-torchai thanks for reporting, we'll take a look. A PR would be appreciated if you feel like you know where they should link.