Change opening to be more specific and clear.

Author: n1cholasv

docs/content/guide/module.ngdoc

@@ -4,9 +4,11 @@
 
 # What is a Module?
 
-Most applications have a main method which instantiates, wires, and bootstraps the application.
-Angular apps don't have a main method. Instead modules declaratively specify how an application
-should be bootstrapped. There are several advantages to this approach:
+Traditional JavaScript embedded in HTML has a main method or similar which instantiates, wires, and bootstraps the application.
+Angular apps don't have a visible main method, but rather declaratively specify on the HTML DOM how an application
+should be bootstrapped as the DOM loads and executes. Modules are where the code associated with that markup exists.
+
+There are several advantages to this approach:
 
   * The process is more declarative which is easier to understand
   * In unit-testing there is no need to load all modules, which may aid in writing unit-tests.