Doc: Fix versioned links on All Classes/QML Types pages

Change-Id: I924c4228a3c5117d87b98ca4643dc3871d205e88
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>

doc/src/classes.qdoc

@@ -58,7 +58,7 @@
     \li \l{All Namespaces}
     \li \l{All Classes by Module}
     \li \l{Obsolete Classes}
-    \li \l{New Classes and Functions in Qt 5.11}
+    \li \l{New Classes and Functions in Qt 5.12}
     \endlist
 
     For more reference pages including QML types, visit \l{Qt Reference Pages}.
@@ -82,7 +82,7 @@
     \li \l{All QML Types}
     \li \l{All QML APIs by Module}
     \li \l{Obsolete QML Types}
-    \li \l{New Classes and Functions in Qt 5.11}
+    \li \l{New Classes and Functions in Qt 5.12}
     \endlist
 
     For more reference pages including C++ APIs, visit \l{Qt Reference Pages}.
@@ -105,7 +105,7 @@
     \li \l{All QML Basic Types}
     \li \l{All QML APIs by Module}
     \li \l{Obsolete QML Types}
-    \li \l{New Classes and Functions in Qt 5.11}
+    \li \l{New Classes and Functions in Qt 5.12}
     \endlist
 
     For more reference pages including C++ APIs, visit \l{Qt Reference Pages}.