Should be Cnx not CNX

Author: Dantemss

app/subsystems/content/models/page.rb

@@ -225,7 +225,7 @@ def fragment_splitter
   end
 end
 
-# Compatibility: Many existing pages have serialized fragments saved as OpenStax::CNX::V1::Fragment
-module OpenStax::CNX
+# Compatibility: Many existing pages have serialized fragments saved as OpenStax::Cnx::V1::Fragment
+module OpenStax::Cnx
   V1 = ::OpenStax::Content
 end