Remove outdated extensions from the reference (#1855)

Author: akukanov

doc/main/reference/examples/parallel_sort_ranges_extension_example.cpp

@@ -16,8 +16,6 @@ It also describes features that are not included in the oneTBB specification.
 .. toctree::
     :titlesonly:
 
-    parallel_for_each_semantics
-    parallel_sort_ranges_extension
     scalable_memory_pools/malloc_replacement_log
     rvalue_reduce