doc,n-api: update N-API version matrix for v12.x

PR-URL: #27745
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

doc/api/n-api.md

@@ -152,6 +152,7 @@ available to the module code.
 | v9.x  | v9.0.0* | v9.3.0*  | v9.11.0* |          |
 | v10.x |         |          | v10.0.0  |          |
 | v11.x |         |          | v11.0.0  | v11.8.0  |
+| v12.x |         |          |          | v12.0.0  |
 
 \* Indicates that the N-API version was released as experimental