Add assets endpoint to api reference

Author: rijkvanzanten

.vuepress/config.js

@@ -115,6 +115,7 @@ module.exports = {
           ["/api/authentication", "Authentication"],
           ["/api/items", "Items"],
           ["/api/files", "Files"],
+          ["/api/assets", "Assets (Thumbnails)"],
           ["/api/activity", "Activity"],
           ["/api/collections", "Collections"],
           ["/api/collection-presets", "Collection Presets"],

api/assets.md

@@ -0,0 +1,80 @@
+---
+pageClass: page-reference
+---
+
+# Assets (Thumbnails)
+
+<two-up>
+
+::: slot left
+Image typed files can be dynamically resized and transformed to fit any need.
+:::
+
+<info-box title="Endpoints" slot="right">
+
+```endpoints
+   GET /:project/assets/:key
+```
+
+</info-box>
+</two-up>
+
+---
+
+## Get an asset
+
+<two-up>
+<template slot="left">
+
+Get a resized file. Files are resized on demand.
+
+### Parameters
+
+<def-list>
+
+!!! include params/project.md !!!
+
+#### key <def-type alert>required</def-type>
+`private_hash` of the file.
+
+</def-list>
+
+### Query
+
+<def-list>
+
+#### key <def-type>optional</def-type>
+The key of the asset size configured in settings.
+
+#### w <def-type>optional</def-type>
+Width of the file in pixels.
+
+#### h <def-type>optional</def-type>
+Height of the file in pixels.
+
+#### f <def-type>optional</def-type>
+Fit. One of `crop`, `contain`.
+
+#### q <def-type>optional</def-type>
+Quality of compression. Number between 1 and 100.
+
+</def-list>
+
+If you're using `key`, you don't need to specify any of the other query parameters. If you're using `w`, `h`, or any of the others, you're required to provide them all. This allows Directus to match it against the whitelist in settings. If you have the whitelist turned off completely, any combination is allowed.
+
+</template>
+<template slot="right">
+<div class="sticky">
+<info-box title="Endpoint">
+
+```endpoints
+   GET /:project/assets/:key
+```
+
+</info-box>
+
+</div>
+</template>
+</two-up>
+
+---

guides/user-guide.md

@@ -285,7 +285,7 @@ The file library is an annex of all files added to Directus. Files may be added
 
 Directus also supports multiple [storage adapters](../extensions/storage-adapters.md), so you may have the option to save files to different locations.
 
-There's also an automatic [thumbnailer](./thumbnailer.md) included, so you can easily save your original files at different sizes. Allowed thumbnail sizes are setup by your administrator.
+There's also an automatic [thumbnailer](./files.md) included, so you can easily save your original files at different sizes. Allowed thumbnail sizes are setup by your administrator.
 
 By default the File Library displays as a Card layout with thumbnails, but you can change this in the [Info Sidebar](#info-sidebar).