Wrong stability state of N-API in the addons docs

Looks like the stability state of N-API [in the addons docs](https://github.com/nodejs/node/blob/master/doc/api/addons.md) is outdated

> Stability: 1 - Experimental

Shouldn't it be 

> Stability: 2 - Stable

?