doc: add async_hooks, n-api to _toc.md and all.md

PR-URL: https://github.com/nodejs/node/pull/13379
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/_toc.md

@@ -6,6 +6,7 @@
 <div class="line"></div>
 
 * [Assertion Testing](assert.html)
+* [Async Hooks](async_hooks.html)
 * [Buffer](buffer.html)
 * [C++ Addons](addons.html)
 * [C/C++ Addons - N-API](n-api.html)

doc/api/all.md

@@ -1,8 +1,10 @@
 @include documentation
 @include synopsis
 @include assert
+@include async_hooks
 @include buffer
 @include addons
+@include n-api
 @include child_process
 @include cluster
 @include cli