doc: fix description of N-API exception handlers

The return value is not a boolean and even if interpreted as one,
it does not indicate whether an exception is pending.

For napi_is_exception_pending, the description of the result parameter
already explains how to check whether an exception is pending.

PR-URL: #30893
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Gabriel Schulhof <gabriel.schulhof@intel.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

doc/api/n-api.md

@@ -1057,8 +1057,6 @@ napi_status napi_get_and_clear_last_exception(napi_env env,
 
 Returns `napi_ok` if the API succeeded.
 
-This API returns true if an exception is pending.
-
 This API can be called even if there is a pending JavaScript exception.
 
 #### napi_is_exception_pending
@@ -1076,8 +1074,6 @@ napi_status napi_is_exception_pending(napi_env env, bool* result);
 
 Returns `napi_ok` if the API succeeded.
 
-This API returns true if an exception is pending.
-
 This API can be called even if there is a pending JavaScript exception.
 
 #### napi_fatal_exception