Add tootip for the KTextEdit widget within environment editor.

The code assumes one environment variable per line, but users may
not guess out that assumption without prompt.

src/EditProfileDialog.cpp

@@ -298,6 +298,8 @@ void EditProfileDialog::showEnvironmentEditor()
     QStringList currentEnvironment = info->property<QStringList>(Profile::Environment);
 
     edit->setPlainText( currentEnvironment.join("\n") );
+    edit->setToolTip( i18n("One environment varible per line" ) );
+
     dialog->setPlainCaption(i18n("Edit Environment"));
     dialog->setMainWidget(edit);