doc: Misc syntax and spelling fixes ...

Tidying up a few Sphinx warnings that had built-up over time.
None of these are critical but it cleans up the Sphinx output.

At the same time, fixing some spelling errors that were detected.

Change-Id: I38209e235481eed287f8008c6de9dedd6b12ab2e
Signed-off-by: Paul Beesley <paul.beesley@arm.com>

amlogic: g12a: Add support for the S905X2 (G12A) platform ...

Introduce the preliminary support for the Amlogic S905X2 (G12A) SoC.

This port is a minimal implementation of BL31 capable of booting
mainline U-Boot and Linux. Tested on a SEI510 board.

Signed-off-by: Carlo Caione <ccaione@baylibre.com>
Change-Id: Ife958f10e815a4530292c45446adb71239f3367f