New design for the widgets section in the docs (#866)

* Initial commit for the new widgets section

* Placing all the widgets and refining the CSS and Hugo logic

* Initial commit for the new widgets section

* Placing all the widgets and refining the CSS and Hugo logic

* Rebased and updated the info according to @verythorough contribution

* Fixing the yaml codes for the relation and select widget sections

* Merging with widgets.md and app.j

* Fixing some silly mistakes (sorry!)

* Following @verythorough contributions :)

* Adding the markdown widget and fixing the widgets container background

* Adding the URL functionality and myself as a contributor :)

* Adding myself as a contributor :)

website/site/content/docs/widgets/hidden.md

@@ -0,0 +1,20 @@
+---
+label: "Hidden"
+target: "hidden"
+type: "widget"
+---
+
+### Hidden
+
+Hidden widgets do not display in the UI. In folder collections that allow users to create new items, you will often want to set a default for hidden fields, so they will be set without requiring an input.
+
+- **Name:** `hidden`
+- **UI:** none
+- **Data type:** any valid data type
+- **Options:** 
+  - `default`: accepts any valid data type; recommended for collections that allow adding new items
+- **Example:**
+
+  ```yaml
+  - {label: "Layout", name: "layout", widget: "hidden", default: "blog"}
+  ```