Adds a link from user-guide.rst to coding-guidelines.rst and merges
the information about using checkpatch from both files into the user
guide document.
Change-Id: Iffbb4225836a042d20024faf28b8bdd6b2c4043e
Signed-off-by: Paul Beesley <paul.beesley@arm.com>
This content has been imported and adapted from the TF GitHub wiki
article 'ARM-Trusted-Firmware-Coding-Guidelines'.
The aim is to increase the visibility of the coding guidelines by
including them as part of the documentation that is within the TF
repository.
Additionally, the documentation can then be linked to by other
documents in the docs/ directory without worrying about broken links
to, for example, the external wiki.
Change-Id: I9d8cd6b5117b707c1a113baeba7fc5e1b4bf33bc
Signed-off-by: Paul Beesley <paul.beesley@arm.com>