remove Jekyll command markers from comment block

fix carpentries/lesson-example#281

Author: fmichonneau

_includes/episode_overview.html

@@ -10,7 +10,7 @@
     questions and objectives, we pass them as parameters to the Liquid's
     `include` statement when we generate the page:
 
-	{% include episode_overview.html teaching_time=e.teaching ... %}
+	 include episode_overview.html teaching_time=e.teaching ...
 
     Here we obtain the information we need either from the episode itself or
     from the parameters passed in.