Remove useless comment now we have variadic templates for ConcurrentRun

ext/libclementine-common/core/concurrentrun.h

@@ -40,12 +40,6 @@
   ThreadFunctor classes are used to store a functor and its arguments, and
   Run() functions are used for convenience: to directly create a new
   ThreadFunctor object and start it.
-
-  Currently, only functions with zero, one, two or three arguments are
-  supported, but other might be added easily for X arguments by defining a new
-  ThreadFunctorX class (and eventually a second class for handling functions
-  which return void: see existing classes for examples), and add new Run()
-  function.
 */