stub out api overview

Author: jderochervlk

pages/docs/manual/v12.0.0/api.mdx

@@ -1,18 +1,17 @@
 # Overview
 
-## ReScript Core
+## Language Features
+Move this section from the docs page? It feels more like a reference?
 
-[Core](api/core) is ReScript's new standard library. It replaces the complete `Js` module as well as some of the more frequently used modules from `Belt` and is recommended to use with uncurried mode.
+## Standard library
+AKA Core
 
-In ReScript 11, it is shipped as a separate npm package `@rescript/core` that is added to your project as per the [installation instructions](/docs/manual/next/installation). In future ReScript versions, it will be included with the `rescript` npm package itself.
+## Syntax lookup
+[Syntax lookup](/syntax-lookup)
 
 ## Additional Libraries
 
 ReScript ships with these two additional modules in its standard library:
 
 - [Belt](api/belt): immutable collections and extra helpers not available in JavaScript / [Core](api/core).
 - [Dom](api/dom): Dom related types and modules. Contains our standardized types used by various userland DOM bindings.
-
-## Legacy Modules
-
-The [Js](api/js) module is superseded by [Core](api/core).