HF audit zkApp docs: o1js Actions & Reducer actions-and-reducer.mdx

[barriebyron]

Audit and update all zkApp docs for technical accuracy prior to hard fork #459 Before the HF, verify technical content in

Actions & Reducer https://docs.minaprotocol.com/zkapps/o1js/actions-and-reducer

123 lines https://github.com/o1-labs/docs2/blob/main/docs/zkapps/o1js/actions-and-reducer.mdx