add preinstall guide

[Redecorating]

includes steps for disabling secure boot, creating an installation usb, etc. This will allow reduction of the amount of duplicated instructions in each distro's install guide.

I haven't edited the other distro guides to rely on these new consolidated instructions so that needs doing (if maintainers want to do that they should be able to add commits to this branch)

[Redecorating]

also @kekrby for the nixos iso's here https://github.com/t2linux/nixos-t2-iso/releases could the release description link to the section in the readme about combining the iso parts? or maybe have those instructions added to the release description. Otherwise the link I put on this wiki page could be changed to the readme instead of the releases page

[AdityaGarg8]

The Gentoo guide needs a lot of work to be done. @EmreTech , or someone else should get it done imo.

[AdityaGarg8]

I did some changes, maybe you could review them as well

[Redecorating]

I did some changes, maybe you could review them as well

That all looks good to me!

[Redecorating]

@NoaHimesaka1873 could you check 12bf95fe89f4d561ff8bd344bb9a11e7b374dcfc when you have time?

[NoaHimesaka1873]

@Redecorating Seems fine.

[EmmmaTech]

The Gentoo guide needs a lot of work to be done. @EmreTech , or someone else should get it done imo.

I'm not actively maintaining the Gentoo guide or T2 Gentoo repos atm, so I would be glad if someone else fixed the guide!

[AdityaGarg8]

@Redecorating, except for the bootcamp resize partition thing, rest everything done.

[Redecorating]

and thank you everyone for helping with this one :)

[AdityaGarg8]

Let’s merge it!

[AdityaGarg8]

Squash the commits or not? I leave it to you @Redecorating