partitioning-cheatsheet.md: Arch Linux ARM installer is no longer the default

Hey 👋 ,

in file [`docs/sw/partitioning-cheatsheet.md:L56`](https://github.com/AsahiLinux/docs/blob/f6f590eb4ccd15c99c165fb4bbd6c492b5fddb2f/docs/sw/partitioning-cheatsheet.md?plain=1#L56) the wiki states: 
```txt
So the installer will (for a normal Asahi Linux = Arch Linux ARM install) create three partitions:
```
which is no longer correct.

Closely related to  #118 