[M] Change in flashrom[master]: Documentation: Add build instructions for meson

[Thomas Heijligen (Code Review)]

Attention is currently required from: Felix Singer, Edward O'Callaghan, Anastasia Klimchuk.

Thomas Heijligen has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/66862 )

Change subject: Documentation: Add build instructions for meson
......................................................................

Patch Set 4:

(2 comments)

File Documentation/building.md:

https://review.coreboot.org/c/flashrom/+/66862/comment/9dcfb9ab_1afd05dc 
PS1, Line 118: ### Windows
             : TODO
> It is working. I just need to write it down properly. […]

Done

File Documentation/building.md:

https://review.coreboot.org/c/flashrom/+/66862/comment/c1a3c7b0_9ddffe62 
PS3, Line 87: pkg install meson ninja cmocka libpci libftdi1
> What about GCC / Clang?

Added,
The C compiler is part of the base system on *BSD. It is always installed.