Doc: use standard wording in \brief commands

QDoc does some magic with the \class and \namespaces
and \brief commands, so the following wording must be used:
"The xxx class yyy ..."

Change-Id: Id231f30e8464898b776888d5423523de404aae34
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/libs/utils/faketooltip.cpp

@@ -35,7 +35,7 @@
 /*!
     \class Utils::FakeToolTip
 
-    \brief A widget that pretends to be a tooltip.
+    \brief The FakeToolTip class is a widget that pretends to be a tooltip.
 
     By default it has Qt::WA_DeleteOnClose set.
 */