Improve documentation

Improve wording consistency, fix types, add more information about
default value, ...

Following component were reworked during this batch:

* AbstractItemViewHeader.qml
* Action.qml
* ActionTextField.qml
* ActionToolBar.qml
* ApplicationItem.qml
* ApplicationWindow.qml
* Avatar.qml
* BasicListItem.qml
* Card.qml
* CardsGridView.qml
* CardsLayout.qml
3 jobs for !407 with work/doc-i in 54 seconds
detached
Status Name Job ID Coverage
  Build
passed android_qt515 #145798
Linux

00:00:19

passed freebsd_qt515 #145799
FreeBSD

00:00:38

passed suse_tumbleweed_qt515 #145797
Linux

00:00:48