Misleading docs for dc_jsonrpc_next_response

The docs for the cffi function `dc_jsonrpc_next_response` say:

https://github.com/chatmail/core/blob/80acc9d46720723f5971d1c38599c2c091f138df/deltachat-ffi/deltachat.h#L6004-L6005

This is misleading because `dc_jsonrpc_instance_t` holds an `Arc` on `Accounts`, so it cannot happen that the underlying `accounts_t` has been dropped.

This sentence in the docs also suggests that for a clean shutdown you can just `dc_accounts_unref` to somehow unblock `dc_jsonrpc_next_response` which would then return `NULL` to then exit a `dc_jsonrpc_next_response` polling loop. But as far as I understand this will not work, for a clean shutdown it is necessary to manually unblock `dc_jsonrpc_next_response` by sending some request (like `get_system_info`) and then manually break the polling loop (e.g. based on a `done` flag which has been set when initiating the shutdown).

I think even just removing these two lines from the docs would improve comprehensibility.