diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index 52bbaa36..36b5adcd 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -18,6 +18,8 @@
 #                     language. This should match one of the scopes listed in
 #                     the grammars.yml file. Use "none" if there is no grammar
 #                     for this language.
+# group             - Name of the parent language. Languages in a group are counted
+#                     in the statistics as the parent language.
 #
 # Any additions or modifications (even trivial) should have corresponding
 # test change in `test/test_blob.rb`.