Remove namespace oneapi::std from oneDPL (#305)

Author: akukanov

source/elements/oneDPL/source/common.rst

@@ -5,7 +5,6 @@
 Namespaces
 ----------
 
-oneDPL uses :code:`namespace oneapi::std` for the subset of the standard C++ library for kernels,
-and uses :code:`namespace oneapi::dpl` for other functionality including Parallel STL algorithms,
-oneDPL execution policies, and extensions.
-
+oneDPL uses :code:`namespace oneapi::dpl` for all its functionality including Parallel STL algorithms,
+oneDPL execution policies, etc. For the subset of the standard C++ library for kernels, the standard class
+and function names are also aliased in :code:`namespace oneapi::dpl`.