Doc: Fixed typo "lamda".

Change-Id: I17a3b324927407b64cabc39a0b90f0ab2e0676be
Reviewed-by: Martin Smith <martin.smith@digia.com>
Reviewed-by: Sze Howe Koh <szehowe.koh@gmail.com>

src/corelib/doc/src/objectmodel/signalsandslots.qdoc

@@ -392,7 +392,7 @@
     compatible with the slot's arguments. Arguments can also be implicitly
     converted by the compiler, if needed.
 
-    You can also connect to functors or C++11 lamdas:
+    You can also connect to functors or C++11 lambdas:
 
     \code
     connect(sender, &QObject::destroyed, [=](){ this->m_objects.remove(sender); });