doc: fix style of n-api.md

PR-URL: #44377
Reviewed-By: Chengzhong Wu <[email protected]>
Reviewed-By: Daeyeon Jeong <[email protected]>
Reviewed-By: Mohammed Keyvanzadeh <[email protected]>
Reviewed-By: Adrian Estrada <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Tobias Nießen <[email protected]>

Author: theanarkh

doc/api/n-api.md

@@ -1189,7 +1189,7 @@ added:
 
 > Stability: 1 - Experimental
 
-````c
+```c
 NAPI_EXTERN napi_status node_api_throw_syntax_error(napi_env env,
                                                     const char* code,
                                                     const char* msg);
@@ -1214,7 +1214,7 @@ napiVersion: 1
 NAPI_EXTERN napi_status napi_is_error(napi_env env,
                                       napi_value value,
                                       bool* result);
-````
+```
 
 * `[in] env`: The environment that the API is invoked under.
 * `[in] value`: The `napi_value` to be checked.