Update main.html

Get rid of alpha version header

Author: mfernandes61

overrides/main.html

@@ -1,7 +1,7 @@
 {% extends "base.html" %}
 
 {% block announce %}
-This lesson is under active development and considered pre-alpha.
+Lesson Release V1.0.
 {% endblock %}
 
 {% block site_meta %}