Fix instruction numbering and script command details

[dyster]

Corrected numbering and clarified script execution instructions in the README.

[Miiraak]

Hi!
Yeah, that's definitely better. 👍🏼

Can you add correction for this one too ? #432

i was sleepy when writing this ^^

[ItzELECTR0]

Hi! This is definitely an improvement.
Could you fix the instructions to account for this issue too?

It would go from:

C:/path/to/your/tiny11/script.ps1 -ISO <inputletter> -SCRATCH <outputletter>

To

powershell -f "C:\path\to\your\tiny11\script.ps1" -ISO <inputletter> -SCRATCH <outputletter>