Clarify QElapsedTimer::hasExpired()'s documentation

The description in terms of timeouts was confusing. Instead, say what
it actually does, in plain terms. Mention that you can do similar for
a duration.

Task-number: QTBUG-115447
Change-Id: I4618d7fa290e7959ed3cb51e5c2576b041f77091
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 669470e2be99dbeef2ec1b2083cf6a86c8c9d917)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/kernel/qelapsedtimer.cpp

@@ -403,10 +403,12 @@ bool QElapsedTimer::isValid() const noexcept
 }
 
 /*!
-    Returns \c true if this QElapsedTimer has already expired by \a timeout
-    milliseconds (that is, more than \a timeout milliseconds have elapsed).
-    The value of \a timeout can be -1 to indicate that this timer does not
-    expire, in which case this function will always return false.
+    Returns \c true if elapsed() exceeds the given \a timeout, otherwise \c false.
+
+    A negative \a timeout is interpreted as infinite, so \c false is returned in
+    this case. Otherwise, this is equivalent to \c {elapsed() > timeout}. You
+    can do the same for a duration by comparing durationElapsed() to a duration
+    timeout.
 
     \sa elapsed(), QDeadlineTimer
 */