Add better deadzone information to Controllers, gamepads, and joysticks tutorial

[dweremeichik]

Your Godot version: Stable (3.3.2)

Issue description:

This page currently boasts the deadzone capability of Godot 4.0. It also explains how a deadzone can benefit your game and lists some default values. What it doesn't do is explain how the default deadzone works. It also doesn't elude to the possibility of using different deadzone types or their use cases.

Related: #5012

Proposal:

Add information akin to: this reference explaining how the default deadzone works and why this may not be an optimal choice for your game.

URL to the documentation page (if already existing):

https://docs.godotengine.org/en/stable/tutorials/inputs/controllers_gamepads_joysticks.html

[dweremeichik]

I found that this is mentioned in the FPS tutorial on this page:
https://docs.godotengine.org/en/stable/tutorials/3d/fps_tutorial/part_four.html?highlight=joy#adding-joypad-input

[stephanbogner]

I'd appreciate this too. The section about deadzones is already really good but I think it's missing:

1. A clear value recommendation, e.g. 0.2. (The current default 0.5 seems arbitrary and makes controls weird if used.)
2. Whether deadzone should be configurable within the game

Regarding 1)
Apparently common values are between 0.1 to 0.2 (Source): For the Ouya-gamepad this developer needed a value of 0.25, for a Xbox 360 gamepad 0.1.

Unfortunately I couldn't find a list of common stick drift values to make a data-based proposal.

Regarding 2)
I think there should be a clear recommendation to make this configurable within your game.

Competitive games, such as Rocket League / Fortnite / Call of Duty have such setting, where pro players choose values as low as 0.05 (probably on very modern expensive gear).

On the other hand it would make sense for casual games too, as those players might use very old, cheap, or knock off gear with high stick drift.