Merge pull request #962 from KhronosGroup/host_concurent

Clarify host concurency access

Author: gmlueck

adoc/chapters/programming_interface.adoc

@@ -3595,8 +3595,8 @@ Indicates that the device supports explicit USM allocations as described in
 --
 Indicates that the device can access USM memory allocated via
 [code]#usm::alloc::host#.
-The device only supports atomic modification of a host allocation if
-[api]#aspect::usm_atomic_host_allocations# is also supported.
+Concurrent access and atomic modification of a host allocation is only supported
+if [api]#aspect::usm_atomic_host_allocations# is also supported.
 (See <<sec:usm>>.)
 --