Documented custom middleware.

Author: jaydenseric

changelog.md

@@ -9,6 +9,7 @@
   - Renamed the `File` input type `Upload` for clarity.
   - Wording and formatting improvements.
   - Covered React Native.
+  - Documented custom middleware.
 
 ## 2.0.2
 

readme.md

@@ -21,7 +21,7 @@ npm install apollo-upload-server
 
 Add the server middleware just before [graphql-server](https://github.com/apollographql/graphql-server).
 
-For [Express](http://expressjs.com):
+#### [Express](http://expressjs.com)
 
 ```js
 import { apolloUploadExpress } from 'apollo-upload-server'
@@ -41,7 +41,7 @@ app.use(
 // ✂
 ```
 
-For [Koa](http://koajs.com):
+#### [Koa](http://koajs.com)
 
 ```js
 import { apolloUploadKoa } from 'apollo-upload-server'
@@ -60,6 +60,14 @@ router.post(
 // ✂
 ```
 
+#### Custom middleware
+
+If the middleware you need is not available, import the asynchronous function `processRequest` to make your own:
+
+```js
+import { processRequest } from 'apollo-upload-server'
+```
+
 ### GraphQL schema
 
 Add an input type for uploads to your schema. You can name it anything but it must have this shape: