Debugger: Describe the "Override server address/channel" field better

Change-Id: I2bd112d1d2f46904513fa668a17f0a07ebe26e12
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: Rainer Keller <Rainer.Keller@qt.io>

src/plugins/debugger/debuggerdialogs.h

@@ -80,6 +80,7 @@ private:
     StartApplicationParameters parameters() const;
     void setParameters(const StartApplicationParameters &p);
     void setHistory(const QList<StartApplicationParameters> &l);
+    void onChannelOverrideChanged(const QString &channel);
 
     StartApplicationDialogPrivate *d;
 };