Fix docs on types

Closes GH-2104.

Author: wooorm

docs/docs/getting-started.server.mdx

@@ -191,6 +191,13 @@ Then you can install and use
 [`@types/mdx`](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/mdx),
 which adds types to import statements of supported files.
 
+You can also import several types about the API of MDX files from `@types/mdx`.
+For example:
+
+```js path="example.ts"
+import type {MDXComponents} from 'mdx/types'
+```
+
 ### Security
 
 Please note that MDX is a programming language.

packages/preact/readme.md

@@ -158,8 +158,13 @@ components.
 
 This package is fully typed with [TypeScript][].
 
-An additional `Components` type is exported, which represents the acceptable
-configuration for the functions and components from this project.
+To enable types for imported `.mdx`, `.md`, etcetera files, you should make sure
+the TypeScript `JSX` namespace is typed.
+This is done by installing and using the types of your framework, as in
+[`preact`](https://github.com/preactjs/preact).
+Then you can install and use
+[`@types/mdx`](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/mdx),
+which adds types to import statements of supported files.
 
 ## Security
 

packages/react/readme.md

@@ -158,8 +158,13 @@ components.
 
 This package is fully typed with [TypeScript][].
 
-An additional `Components` type is exported, which represents the acceptable
-configuration for the functions and components from this project.
+To enable types for imported `.mdx`, `.md`, etcetera files, you should make sure
+the TypeScript `JSX` namespace is typed.
+This is done by installing and using the types of your framework, such as
+[`@types/react`](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/react).
+Then you can install and use
+[`@types/mdx`](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/mdx),
+which adds types to import statements of supported files.
 
 ## Security
 

packages/vue/readme.md

@@ -127,9 +127,6 @@ Get current components from the MDX Context.
 
 This package is fully typed with [TypeScript][].
 
-An additional `Components` type is exported, which represents the acceptable
-configuration for the functions and components from this project.
-
 ## Security
 
 See [§ Security][security] on our website for information.