Fix typo in title: corrected missing brackets in sequence-to-sequence…

… models

chapters/en/chapter1/7.mdx

@@ -1,4 +1,4 @@
-# Sequence-to-sequence models[sequence-to-sequence-models]
+# Sequence-to-sequence models[[sequence-to-sequence-models]]
 
 <CourseFloatingBanner
     chapter={1}