setup new docs.comma.ai (#32813)

* start with mkdocs

* some structure

* little more

docs/new/docs/car-porting/brand-port.md

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+# Developing a car brand port
+
+A brand port is a port of openpilot to a substantially new car brand or platform within a brand.
+
+Here's an example of one: https://github.com/commaai/openpilot/pull/23331.

docs/new/docs/car-porting/model-port.md

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+# Developing a car model port
+
+A model port is a port of openpilot to a new car model within an already supported brand. Model ports are easier than brand ports because the car's existing APIs are already known.
+
+Here's an example of one: https://github.com/commaai/openpilot/pull/30672/.

docs/new/docs/car-porting/what-is-a-car-port.md

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+# What is a car port?
+
+All car ports live in `openpilot/selfdrive/car/`.
+
+* interface.py: Interface for the car, defines the CarInterface class
+* carstate.py: Reads CAN from car and builds openpilot CarState message
+* carcontroller.py: Builds CAN messages to send to car
+* values.py: Limits for actuation, general constants for cars, and supported car documentation
+* radar_interface.py: Interface for parsing radar points from the car

docs/new/docs/getting-started/what-is-openpilot.md

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+# What is openpilot?
+
+[openpilot](http://github.com/commaai/openpilot) is an open source driver assistance system. Currently, openpilot performs the functions of Adaptive Cruise Control (ACC), Automated Lane Centering (ALC), Forward Collision Warning (FCW), and Lane Departure Warning (LDW) for a growing variety of [supported car makes, models, and model years](docs/CARS.md). In addition, while openpilot is engaged, a camera-based Driver Monitoring (DM) feature alerts distracted and asleep drivers. See more about [the vehicle integration](docs/INTEGRATION.md) and [limitations](docs/LIMITATIONS.md).
+
+
+## How do I use it?
+
+openpilot is designed to be used on the comma 3X.
+
+## How does it work?
+
+In short, openpilot uses the car's existing APIs for the built-in [ADAS](https://en.wikipedia.org/wiki/Advanced_driver-assistance_system) system and simply provides better acceleration, braking, and steering inputs than the stock system.

docs/new/docs/how-to/turning-the-speed-blue.md

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+This section is for how-to's on common workflows.
+
+They'll be like this blog post we wrote:
+https://blog.comma.ai/turning-the-speed-blue/