docs: stub viewer configuration

docs/latest/viewer/configuration.md

@@ -1,3 +1,56 @@
 # Viewer: Configuration
 
-...
+We maintain a number of common viewer application configurations at [`<root>/platform/viewer/public/configs`][config-dir]. How these values are passed to the viewer depend on how it's deployed, but the two most common paths are:
+
+- `index.html` looks for `https://your-website.com/app-config.js` OR
+- `index.html` passes the values to `OHIF.installViewer()`
+
+```js
+window.config = {
+  routerBasename: '/',
+  whiteLabelling: {},
+  extensions: [],
+  showStudyList: true,
+  filterQueryParam: false,
+  servers: {
+    dicomWeb: [
+      {
+        name: 'DCM4CHEE',
+        wadoUriRoot: 'https://server.dcmjs.org/dcm4chee-arc/aets/DCM4CHEE/wado',
+        qidoRoot: 'https://server.dcmjs.org/dcm4chee-arc/aets/DCM4CHEE/rs',
+        wadoRoot: 'https://server.dcmjs.org/dcm4chee-arc/aets/DCM4CHEE/rs',
+        qidoSupportsIncludeField: true,
+        imageRendering: 'wadors',
+        thumbnailRendering: 'wadors',
+        enableStudyLazyLoad: true,
+      },
+    ],
+  },
+  // Supported Keys: https://craig.is/killing/mice
+  hotkeys: [
+    { commandName: 'rotateViewportCW', label: 'Rotate Right', keys: ['r'] },
+    { commandName: 'rotateViewportCCW', label: 'Rotate Left', keys: ['l'] },
+    { commandName: 'invertViewport', label: 'Invert', keys: ['i'] },
+    {
+      commandName: 'flipViewportVertical',
+      label: 'Flip Horizontally',
+      keys: ['h'],
+    },
+    {
+      commandName: 'flipViewportHorizontal',
+      label: 'Flip Vertically',
+      keys: ['v'],
+    },
+  ],
+  // Config to pass to the bundled cornerstone extension
+  cornerstoneExtensionConfig: {},
+};
+```
+
+<!--
+  LINKS
+-->
+
+<!-- prettier-ignore-start -->
+[config-dir]: https://github.com/OHIF/Viewers/tree/master/platform/viewer/public/config
+<!-- prettier-ignore-end -->