Updated the Devices section

[jo-unity]

I updated the Devices section of the user manual. Pages I was most concerned with:

* [Devices](devices.md)
  * [Types of input devices](devices-overview.md)
  * [Pointer devices](devices-pointers.md)
      * [Pointer devices introduction](pointers-introduction.md)
      * [Touch devices](devices-touch.md)
        * [Touch devices introduction](touch-introduction.md)
        * [Polling touch input](touch-polling.md)
        * [Simulate touch input](simulate-touch-input.md)
        * [Bind touch input to an action](bind-touch-input.md)
      * [Mouse devices](devices-mouse.md)
        * [Mouse devices introduction](mouse-introduction.md)
        * [Query and control mouse devices in code](query-mouse-devices.md)
      * [Pen devices](devices-pen.md)
        * [Pen devices introduction](pen-introduction.md)
        * [Query pen devices in code](query-pen-devices.md)
  * [Keyboards](devices-keyboard.md)
    * [Keyboards introduction](keyboards-introduction.md)
    * [Query keyboards in code](query-keyboards.md)
    * [Read text input](read-keyboard-text-input.md)
  * [Joysticks](devices-joysticks.md)
  * [Gamepads](devices-gamepads.md)
    * [Gamepads introduction](gamepads-introduction.md)
    * [PlayStation gamepads](gamepads-playstation.md)
    * [Switch gamepads](gamepads-switch.md)
    * [Xbox gamepads](gamepads-xbox.md)
    * [Query and control gamepads in code](query-gamepads.md)
    * [Polling gamepad input](gamepad-polling.md)
    * [Gamepad haptics](gamepad-haptics.md)
  * [Sensors](devices-sensors.md)
    * [Sensors introduction](sensors-introduction.md)
    * [Query sensors in code](query-sensors.md)
    * [Supported sensors reference](supported-sensors-reference.md)
  * [Human Interface Device specification](hid-specification.md)
    * [Human Interface Device specification introduction](hid-specification-introduction.md)
    * [Create a custom device layout](hid-create-custom-layout.md)
    * [Use an existing input device to create a layout](hid-create-custom-layout-existing.md)
    * [Use a custom class to create a layout](hid-create-custom-layout-class.md)
  * [Supported devices reference](supported-devices-reference.md)

NOTE: The "Supported Devices Reference" page needs validation from devs. Much of the information might be wrong. General feedback on the layout is appreciated, but the details of the content are likely to change in a future PR.

[unity-cla-assistant]

All committers have signed the CLA.

[siobhan-unity]

I think the structure looks great, the pages have clear goals and types.

I would suggest another look at the descriptions for pages that appear on landing pages, as the content model recommends that they always begin with verbs (even for concept and reference pages), and there are a few landing pages that don't follow this advice.

Everything else looks all good to me!