[SYCL][Doc] Clarify ways to set sub-group sizes (intel#10118)

The sycl_ext_oneapi_kernel_properties extension doesn't explain that the
various sub-group size properties are compatible with the
SYCL_EXT_ONEAPI_FUNCTION_PROPERTY macro, so clarify that in
sycl_ext_oneapi_named_sub_group_sizes.

Signed-off-by: John Pennycook <john.pennycook@intel.com>

sycl/doc/extensions/proposed/sycl_ext_oneapi_named_sub_group_sizes.asciidoc

@@ -20,7 +20,7 @@
 == Notice
 
 [%hardbreaks]
-Copyright (C) 2019-2022 Intel Corporation.  All rights reserved.
+Copyright (C) 2019-2023 Intel Corporation.  All rights reserved.
 
 Khronos(R) is a registered trademark and SYCL(TM) and SPIR(TM) are trademarks
 of The Khronos Group Inc.  OpenCL(TM) is a trademark of Apple Inc. used by
@@ -212,6 +212,12 @@ NOTE: No special handling is required to detect this case, since
 `sub_group_size_primary` and `sub_group_size_automatic` are simply named
 shorthands for properties associated with `sub_group_size_key`.
 
+The `sub_group_size`, `sub_group_size_primary` and `sub_group_size_automatic`
+properties can be associated with a kernel launch using one of the overloaded
+kernel invocation commands or associated with a kernel definition using the
+`get(properties_tag)` mechanism. The properties can be associated with a device
+function using the `SYCL_EXT_ONEAPI_FUNCTION_PROPERTY` macro.
+
 There are special requirements whenever a device function defined in one
 translation unit makes a call to a device function that is defined in a second
 translation unit. In such a case, the second device function is always declared