Change in coreboot[master]: Documentation: Codify some guidelines for headers and chain-including

[Angel Pons (Code Review)]

Attention is currently required from: Martin Roth, Julius Werner.
Angel Pons has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/50247 )

Change subject: Documentation: Codify some guidelines for headers and chain-including
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Patch Set 1: Code-Review+1

(1 comment)

File Documentation/coding_style.md:

https://review.coreboot.org/c/coreboot/+/50247/comment/fc6b64ce_c2357b72 
PS1, Line 876: take advantage of the macro
take advantage of the `ARRAY_SIZE` macro: