doc: clarify behavior of napi_get_typedarray_info

Signed-off-by: Michael Dawson <michael_dawson@ca.ibm.com>

Fixes: https://github.com/nodejs/node/issues/32089

PR-URL: https://github.com/nodejs/node/pull/32603


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>