QTimer: Doc: Distribute existing note to useful places

Amends 146749f9b7

Pick-to: 6.8 6.10
Change-Id: Id4e861faaf1d268692ec496fdcb2e69c8acd694f
Reviewed-by: Paul Wicking <paul.wicking@qt.io>

src/corelib/kernel/qtimer.cpp

@@ -205,6 +205,11 @@ Qt::TimerId QTimer::id() const
 //! [singleshot-activation]
     If \l singleShot is true, the timer will be activated only once.
 //! [singleshot-activation]
+
+//! [eventloop-busy]
+    \note   Keeping the event loop busy with a zero-timer is bound to
+            cause trouble and highly erratic behavior of the UI.
+//! [eventloop-busy]
 */
 void QTimer::start()
 {
@@ -236,8 +241,7 @@ void QTimer::start()
 
     \include timers-common.qdocinc negative-intervals-not-allowed
 
-    \note   Keeping the event loop busy with a zero-timer is bound to
-            cause trouble and highly erratic behavior of the UI.
+    \include qtimer.cpp eventloop-busy
 */
 void QTimer::start(int msec)
 {
@@ -277,6 +281,8 @@ checkInterval(const char *caller, std::chrono::milliseconds interval)
     \include qtimer.cpp singleshot-activation
 
     \include timers-common.qdocinc negative-intervals-not-allowed
+
+    \include qtimer.cpp eventloop-busy
 */
 void QTimer::start(std::chrono::milliseconds interval)
 {
@@ -631,6 +637,8 @@ QBindable<bool> QTimer::bindableSingleShot()
     interval of 0 will time out as soon as all the events in the window
     system's event queue have been processed.
 
+    \include qtimer.cpp eventloop-busy
+
     Setting the interval of a running timer will change the interval,
     stop() and then start() the timer, and acquire a new id().
     If the timer is not running, only the interval is changed.