doc: avoid referring to C array size

The size of arrays is measured in bytes in C, not in the number of
elements. The napi_get_cb_info function takes the length of the
array, that is, the number of elements it can contain, and not its size.

PR-URL: nodejs#35300
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Michael Dawson <midawson@redhat.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Gabriel Schulhof <gabriel.schulhof@intel.com>

doc/api/n-api.md

@@ -4392,8 +4392,8 @@ napi_status napi_get_cb_info(napi_env env,
 
 * `[in] env`: The environment that the API is invoked under.
 * `[in] cbinfo`: The callback info passed into the callback function.
-* `[in-out] argc`: Specifies the size of the provided `argv` array and receives
-  the actual count of arguments.
+* `[in-out] argc`: Specifies the length of the provided `argv` array and
+  receives the actual count of arguments.
 * `[out] argv`: Buffer to which the `napi_value` representing the arguments are
   copied. If there are more arguments than the provided count, only the
   requested number of arguments are copied. If there are fewer arguments