[M] Change in coreboot[master]: /: Update and rewrite README.md

[Angel Pons (Code Review)]

Attention is currently required from: Felix Singer, Martin L Roth, Matt DeVillier, Martin Roth.

Angel Pons has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/67119 )

Change subject: /: Update and rewrite README.md
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Patch Set 4: Code-Review+1

(3 comments)

File README.md:

https://review.coreboot.org/c/coreboot/+/67119/comment/efe31de3_c8306513 
PS4, Line 27: `git clone https://review.coreboot.org/coreboot.git%60.
Maybe point to `https://review.coreboot.org/admin/repos/coreboot,general%60 as it includes the command? In case something changes in Gerrit

https://review.coreboot.org/c/coreboot/+/67119/comment/fd5e0e1a_6cbbb3ea 
PS4, Line 37: suggest
What does "suggest" mean here?

https://review.coreboot.org/c/coreboot/+/67119/comment/5f43c415_623b5f12 
PS4, Line 179: 
There's also commonlib/bsd, should it be mentioned?