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/classnamevalidatinglineedit.cpp

@@ -37,7 +37,8 @@
 /*!
     \class Utils::ClassNameValidatingLineEdit
 
-    \brief A Line edit that validates a C++ class name and emits a signal
+    \brief The ClassNameValidatingLineEdit class implements a line edit that
+    validates a C++ class name and emits a signal
     to derive suggested file names from it.
 */