Reword documentation updates

Signed-off-by: Artem Gindinson <artem.gindinson@intel.com>

Author: Artem Gindinson

sycl/doc/CompilerAndRuntimeDesign.md

@@ -549,11 +549,11 @@ is then passed to the offload wrapper tool.
 ##### Checking if the compiler is targeting NVPTX
 
 When the SYCL compiler is in device mode and targeting the NVPTX backend,
-compiler defines the macro `__NVPTX__` alongside the
-`__SYCL_DEVICE_ONLY` macro. This macro combination can safely be used
-to enable NVPTX specific code path in SYCL kernels.
+the compiler defines `__SYCL_DEVICE_ONLY__` and `__NVPTX__` macros. This
+macro combination can safely be used to enable NVPTX specific code
+path in SYCL kernels.
 
-*Note: this macro is defined only during the device compilation phase.*
+*Note: these macros are defined only during the device compilation phase.*
 
 ##### NVPTX Builtins