Minor tweak for Rev. 2 of SPIR-V 1.4.
diff --git a/include/spirv/unified1/spirv.core.grammar.json b/include/spirv/unified1/spirv.core.grammar.json
index 14bf5d3..0fb6059 100644
--- a/include/spirv/unified1/spirv.core.grammar.json
+++ b/include/spirv/unified1/spirv.core.grammar.json
@@ -114,7 +114,7 @@
     },
     {
       "tag"     : "Group",
-      "heading" : "Group Instructions"
+      "heading" : "Group and Subgroup Instructions"
     },
     {
       "tag"     : "Device-Side_Enqueue",