Add doc comment for `BUILTIN_MAPPINGS`

build/syntax_mapping.rs

@@ -174,7 +174,8 @@ impl MappingList {
         let len = array_items.len();
 
         format!(
-            "pub(crate) static BUILTIN_MAPPINGS: [(Lazy<Option<GlobMatcher>>, MappingTarget); {len}] = [\n{items}\n];",
+            "/// Generated by build script from /src/syntax_mapping/builtins/.\n\
+            pub(crate) static BUILTIN_MAPPINGS: [(Lazy<Option<GlobMatcher>>, MappingTarget); {len}] = [\n{items}\n];",
             items = array_items.join(",\n")
         )
     }