avicii: Update build version to U

battery: {removable: False, capacity: 4115, tech: 'Li-Po'}

before_install_file_name: before_install_needs_specific_android_fw

before_install_args: {version: 12}

before_recovery_install_file_name: before_recovery_install_boot_stack

before_recovery_install: {instructions: 'boot_stack', partitions: [dtbo, vbmeta]}

bluetooth: {spec: '5', profiles: [A2DP + aptX HD]}

cameras:

- {flash: 'LED', info: '48 MP + 8 MP (Ultra Wide) + 5 MP (Depth) + 2 MP (Macro)'}

width: 63.3 mm (2.88 in)

wifi: 802.11 a/b/g/n/ac, Dual-band, Wi-Fi Direct, Wi-Fi Display, DLNA, Hotspot

community_doc_url: https://community.e.foundation/t/oneplus-nord-avicci-documentation-suggestions/33998

build_version_dev: T

build_version_stable: S

build_version_dev: U

build_version_stable: U

is_lineageos_official: false

can_rollback: true

removable_battery: 0

- { mode: Community install doc }

- { mode: Roll-back, url: null }

oem_unlock_file_name: oem_unlock_generic

recovery_install_command: fastboot flash recovery

recovery_install_file_name: recovery_install_fastboot_generic

install_e_file_name: install_e_with_erecovery

downloads_file_name: device_downloads_erecovery

install_e_file_name: install_e_avicii

help_file_name: help_oneplus

safetynet:  2

rootbeer_pass:  1

## Installing /e/OS 

{% include alerts/tip.html content="For Windows users, we advise to use Git Bash. For more info about Downloads and Installation see [Official Documentation](https://git-scm.com/about)"%}

1. Unzip the archive

    ```

    unzip <fileyoudownloaded>

    ```

   > Replace `<fileyoudownloaded>` with the name of the archive file you downloaded.

   > Alternately you can create a folder and unzip the archive there.

1. Confirm that extracted directory contains following content:

    - `bin-linux-x86 directory` - which contains linux tools including fastboot and adb

    - `bin-msys directory` - which contains Windows tools including fastboot and adb

    - `img files` - The `img` files that are to be flashed onto the device.

    - `flash_avicii_factory.sh` - The installer script.

1. Boot into bootloader/fastboot mode.

    - Power OFF the device.

    - While holding `Volume Down` button, plug in a USB Cable that's connected to a PC on the other end.

1. Run the installer script on Terminal(Linux) or on Git Bash UI(Windows).

    - Make sure you are in the current directory which contains the `flash_avicii_factory.sh` file.

    **Linux**

    - Right click -> Open terminal here

    - Execute the following command:

    ```

    chmod +x flash_avicii_factory.sh && ./flash_avicii_factory.sh

    ``` 

    **Windows**

    - Right click -> Git Bash here

    - Execute the following command:

    ```

    chmod +x flash_avicii_factory.sh && ./flash_avicii_factory.sh

    ```

    The script will flash all required files.