Doc: Reformat, fix some markups

Text is unchanged, but the markup has seen some changes. A couple of \c
were added around code constructs where that was missing and the \uicontrol
cleanups were applied.

Change-Id: I0f9e840f831d777a82665316a7d42b94eb1f8574
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@theqtcompany.com>