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/submiteditorfile.cpp

@@ -35,7 +35,8 @@ using namespace VcsBase::Internal;
 /*!
     \class VcsBase::Internal::SubmitEditorFile
 
-    \brief A non-saveable IDocument for submit editor files.
+    \brief The SubmitEditorFile class provides a non-saveable IDocument for
+    submit editor files.
 */
 
 SubmitEditorFile::SubmitEditorFile(const QString &mimeType, QObject *parent) :