another exclusion line for language stats

.gitattributes

@@ -1,5 +1,7 @@
+# use https://github.com/github-linguist/linguist/blob/master/docs/overrides.md
+# to exclude generated and docs from being included in language stats
 # exclude obsolete code
-src/obsolete/** linguist-documentation
+src/obsolete/* linguist-documentation
 # exclude some documentation
 website/html_root/** linguist-documentation
 website/reference/** linguist-documentation