[NFC][SYCL] Update cl::intel_reqd_sub_group_size attribute documentation (#1009)

Signed-off-by: Dmitry Sidorov <[email protected]>

Author: MrSidims

clang/include/clang/Basic/AttrDocs.td

@@ -3310,7 +3310,8 @@ must be compiled and executed with a sub-group of size n. The value of n must be
 set to a sub-group size supported by the device, or device compilation will fail.
 
 In addition to device functions, the required sub-group size attribute may also
-be specified in the definition of a named functor object, as in the example below:
+be specified in the definition of a named functor object and lambda functions,
+as in the examples below:
 
 .. code-block:: c++
 
@@ -3322,6 +3323,11 @@ be specified in the definition of a named functor object, as in the example belo
       }
   }
 
+  kernel<class kernel_name>(
+  []() [[cl::intel_reqd_sub_group_size(n)]] {
+       /* kernel code */
+  });
+
 See Sub-groups for NDRange Parallelism proposal in sycl/doc/extensions/sub_group_ndrange/sub_group_ndrange.md
   }];
 }

sycl/doc/extensions/SubGroupNDRange/SubGroupNDRange.md

@@ -35,7 +35,7 @@ In keeping with Section 6.7 of the SYCL 1.2.1 specification, attributes are made
 
 The `[[cl::intel_reqd_sub_group_size(n)]]` attribute indicates that the kernel must be compiled and executed with a sub-group of size `n`.  The value of `n` must be set to a sub-group size supported by the device, or device compilation will fail.
 
-In addition to device functions, the required sub-group size attribute may also be specified in the definition of a named functor object, as in the example below:
+In addition to device functions, the required sub-group size attribute may also be specified in the definition of a named functor object and lambda functions, as in the examples below:
 
 ```c++
 class Functor
@@ -45,6 +45,11 @@ class Functor
         /* kernel code */
     }
 }
+
+kernel<class kernel_name>(
+[]() [[cl::intel_reqd_sub_group_size(n)]] {
+     /* kernel code */
+});
 ```
 
 # Sub-group Queries