[docs] incorrect link to json-encode page

[practicalli-johnny]

The Cloudwatch logs publisher readme, along with other publisher pages, have an incorrect link to the json-encode page.
https://github.com/BrunoBonacci/mulog/blob/master/doc/publishers/cloudwatch-logs-publisher.md

The link should point to
https://github.com/BrunoBonacci/mulog/blob/master/doc/json-encode.md