[S] Change in flashrom[master]: tree: Rename master branch to main

[Anastasia Klimchuk (Code Review)]

Attention is currently required from: Patrick Georgi, Stefan Reinauer, Thomas Heijligen.

Anastasia Klimchuk has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/75706?usp=email )

Change subject: tree: Rename master branch to main
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Patch Set 2:

(3 comments)

Commit Message:

https://review.coreboot.org/c/flashrom/+/75706/comment/025bde69_3c175823 :
PS1, Line 7: Switch over master branch to main
> Rename master branch to main […]

Done

Patchset:

PS1:
> Here are new Dev guidelines! CB:75906 :)

I updated dev guide and uploaded new patchset.

Patchset:

PS2: 
I think this patch can be reviewed/approved now, but it needs to be submitted only after the branch is actually renamed (ideally as soon as possible after the renaming).