lesson_check.py: require _config.yml too

diff --git a/bin/lesson_check.py b/bin/lesson_check.py
index 84c28f37c5300fea1e065f1be06196b60cc4db7f..78d78b2dfbf5f013da7ed074379f0a5d83ca5f86 100755 (executable)
--- a/bin/lesson_check.py
+++ b/bin/lesson_check.py
@@ -35,6 +35,7 @@ REQUIRED_FILES = {
     '%/README.md': False,
     '%/_extras/discuss.md': True,
     '%/_extras/guide.md': True,
+    '%/_config.yml': True,
     '%/index.md': True,
     '%/reference.md': True,
     '%/setup.md': True,