QObject: code snippets cleanup

Use chrono literals; remove comment about C++14.

Change-Id: I1594780946dd3e646b5a4f68dad4996f0572f317
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 81e3d10ca5913a79f5e53043bfd33d03f25253f5)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/doc/snippets/code/src_corelib_kernel_qobject.cpp

@@ -106,19 +106,11 @@ protected:
 MyObject::MyObject(QObject *parent)
     : QObject(parent)
 {
-    startTimer(50);     // 50-millisecond timer
-    startTimer(1000);   // 1-second timer
-    startTimer(60000);  // 1-minute timer
+    using namespace std::chrono_literals;
 
-    using namespace std::chrono;
-    startTimer(milliseconds(50));
-    startTimer(seconds(1));
-    startTimer(minutes(1));
-
-    // since C++14 we can use std::chrono::duration literals, e.g.:
-    startTimer(100ms);
+    startTimer(50ms);
     startTimer(5s);
-    startTimer(2min);
+    startTimer(10min);
     startTimer(1h);
 }