Adding JSON & Hashmap Ziglings

[Sagi]

I really enjoyed doing all the exercises but I was missing exercises relating to JSON & Hashmaps.

I was wondering if the project will accept PRs in which some exercises will be added in the following topics:

[ ] Parsing JSON strings to structs
[ ] Parsing JSON strings to a hashmap
[ ] Parsing struct to JSON string
[ ] Parsing hashmap to JSON string

[Chris Boesch]

I was wondering if the project will accept PRs

Only on Codeberg: https://ziglings.org