boards/chromebooks: add jacuzzi board documentation

Signed-off-by: Ricardo Cañuelo <ricardo.canuelo@collabora.com>

content/boards/chromebooks/boards/jacuzzi.md

+---
+title: Jacuzzi Chromebooks
+---
+
+`jacuzzi` is a board name for arm64 Chromebooks based on the Mediatek
+MT8183 SoC. It's an evolution of `kukui`.
+
+The `jacuzzi` Chromebook we're currently using in the lab is an [Acer
+Chromebook Spin
+311](https://www.acer.com/ac/en/US/content/series/acerchromebookspin311)
+(codename `juniper`).
+
+### Debugging interfaces
+
+`jacuzzi` boards have been flashed and tested with [Servo
+v4](../../01-debugging_interfaces) interfaces.
+
+The Acer Chromebook Spin 311 supports CCD and can be debugged through
+its only USB-C port.
+
+#### Network connectivity
+
+The Servo v4 interface includes an Ethernet interface with a chipset
+supported by Depthcharge (R8152).
+
+#### Known issues
+
+No specific issues found for this Chromebook yet, but see [Common
+issues](../common_issues.md).
+
+### Example kernel command line arguments
+
+An example of kernel command line arguments to boot a FIT image:
+
+```
+earlyprintk=ttyS0,115200n8 console=tty1 console_msg_format=syslog console=ttyS0,115200n8 root=/dev/ram0 ip=dhcp tftpserverip=<server_ip>
+```