doc: add ESM doc to _toc.md and all.md

PR-URL: https://github.com/nodejs/node/pull/15248
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/_toc.md

@@ -19,6 +19,7 @@
 * [Deprecated APIs](deprecations.html)
 * [DNS](dns.html)
 * [Domain](domain.html)
+* [ECMAScript Modules](esm.html)
 * [Errors](errors.html)
 * [Events](events.html)
 * [File System](fs.html)

doc/api/all.md

@@ -14,6 +14,7 @@
 @include deprecations
 @include dns
 @include domain
+@include esm
 @include errors
 @include events
 @include fs