Remove strange, incoherent sentences in QColor docs

There were some strange sentences that did not add to the documentation
of HSL vs. HSV.

Task-number: QTBUG-52483
Change-Id: I5f2b8c3bd420fe9cabc74a94af4b78945723b6cf
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

src/gui/painting/qcolor.cpp

@@ -545,12 +545,8 @@ static QStringList get_colornames()
 
     \section1 The HSL Color Model
 
-    HSL is similar to HSV. Instead of value parameter from HSV,
-    HSL has the lightness parameter.
-    The lightness parameter goes from black to color and from color to white.
-    If you go outside at the night its black or dark gray. At day its colorful but
-    if you look in a really strong light a things they are going to white and
-    wash out.
+    HSL is similar to HSV, however instead of the Value parameter, HSL
+    specifies a Lightness parameter.
 
     \section1 The CMYK Color Model