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>
diff --git a/docs/plat/marvell/porting.rst b/docs/plat/marvell/porting.rst
index 8fc1c1f..0a71dbd 100644
--- a/docs/plat/marvell/porting.rst
+++ b/docs/plat/marvell/porting.rst
@@ -112,7 +112,7 @@
 
     .. seealso::
         For XFI/SFI comphy type there is procedure "rx_training" which eases
-        process of suiting some of the parameters. Please see :ref:`uboot_cmd`
+        process of suiting some of the parameters. Please see *uboot_cmd*
         section: rx_training.
 
     The PHY porting layer simplifies updating static values per board type,