qfloat16: use new \compares command

... to describe the comparison operators provided by this class.

Task-number: QTBUG-119433
Pick-to: 6.7
Change-Id: Ifde49fb60aa50b733a35aa01c7a031b82fb06836
Reviewed-by: Marc Mutz <marc.mutz@qt.io>

src/corelib/global/qfloat16.cpp

@@ -23,6 +23,15 @@ QT_IMPL_METATYPE_EXTERN(qfloat16)
     \inheaderfile QFloat16
     \brief Provides 16-bit floating point support.
 
+    \compares partial
+    \compareswith partial float double {long double} qint8 quint8 qint16 quint16 \
+                  qint32 quint32 long {unsigned long} qint64 quint64
+    \endcompareswith
+    \compareswith partial qint128 quint128
+    Comparison with 128-bit integral types is only supported if Qt provides
+    these types.
+    \endcompareswith
+
     The \c qfloat16 class provides support for half-precision (16-bit) floating
     point data.  It is fully compliant with IEEE 754 as a storage type.  This
     implies that any arithmetic operation on a \c qfloat16 instance results in