[M] Change in coreboot[master]: Documentation/contributing: Add Sign-off procedure

[Nicholas Chin (Code Review)]

Nicholas Chin has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/74825 )

Change subject: Documentation/contributing: Add Sign-off procedure
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Patch Set 1:

(1 comment)

Patchset:

PS1: 
This isn't strictly related to Gerrit, but a lot of the contribution stuff is on this page. Taking inspiration from the comments on commit fb47404cb1 (developers.html: Add the sign-off procedure) from the homepage repo, perhaps Gerrit specific guidelines and general contribution guidelines could be split up in the future, as this page is rather long.