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/plugins/vcsbase/nicknamedialog.cpp

@@ -43,7 +43,7 @@ enum { NickNameRole = Qt::UserRole + 1 };
 /*!
     \class VcsBase::Internal::NickNameDialog
 
-    \brief Show users from mail cap file.
+    \brief The NickNameDialog class shows users from a mail cap file.
 
     Manages a list of users read from an extended
     mail cap file, consisting of 4 columns:  "Name Mail [AliasName [AliasMail]]".