Move stuff from readme

Enabling-the-widget.md

@@ -0,0 +1,35 @@
+1. Serve everything under `web/` using your webserver of choice. Make sure not
+   to serve the top-level data, as `config.json` and the Telethon session file
+   contain sensitive data.
+2. Using `/devtools` in Element Web, edit the `m.widgets` account data event to
+   have the following content:
+
+   ```json
+   {
+       "stickerpicker": {
+           "content": {
+               "type": "m.stickerpicker",
+               "url": "https://your.sticker.picker.url/?theme=$theme",
+               "name": "Stickerpicker",
+               "data": {}
+           },
+           "sender": "@you:picker.url",
+           "state_key": "stickerpicker",
+           "type": "m.widget",
+           "id": "stickerpicker"
+       }
+   }
+   ```
+
+    If you do not yet have a `m.widgets` event, simply create it with that content.
+    You can also [use the client-server API directly][1] instead of using Element Web.
+
+    The `theme=$theme` query parameter will make the widget conform to Element's
+    theme automatically. You can also use `light`, `dark` or `black` instead of
+    `$theme` to always use a specific theme.
+
+    You can use https://maunium.net/stickers-demo/ as the URL to try out the
+    picker without hosting the files yourself.
+3. Open the sticker picker and enjoy the fast sticker picking experience.
+
+[1]: https://matrix.org/docs/spec/client_server/latest#put-matrix-client-r0-user-userid-account-data-type