Docs: Fix spelling errors and rendering

* Fix spelling errors in the ADI platform readme.rst
* Fix grammar error in coding_style.rst
* Fix rendering of .h / .c in coding_style.rst

Signed-off-by: Antonio de Angelis <antonio.deangelis@arm.com>
Change-Id: Idca929dbcbce74884924faed2012e3604f3b7229
2 files changed