fix(ngdoc/templates): move module installation above description

When learning about an Angular module, it is not obvious sometimes that
a module is external from looking at the docs and trying to learn about it.

Example: ngMessages.

If you never used it before, you might think it comes with Angular and waste
time on debugging why it is not working.

Like on any github readme.md file, I think it might be better to start the
doc with the installation requirements to indicate this is an external module
you need to bower/npm install

Closes #134

Author: shairez

ngdoc/templates/api/module.template.html

@@ -5,8 +5,6 @@ <h1>
   {% if doc.title %}{$ doc.title | marked $}{% else %}{$ doc.name | code $}{% endif %}
 </h1>
 
-{$ doc.description | marked $}
-
 {% if doc.name != 'ng' and doc.name != 'auto' %}
   <h2>Installation</h2>
 
@@ -41,6 +39,8 @@ <h2>Installation</h2>
   <p>With that you&apos;re ready to get started!</p>
 {% endif %}
 
+{$ doc.description | marked $}
+
 <div class="component-breakdown">
   <h2>Module Components</h2>
   {% for componentGroup in doc.componentGroups %}
@@ -67,4 +67,4 @@ <h2>Usage</h2>
   {$ doc.usage | marked $}
 {% endif %}
 
-{% endblock %}
+{% endblock %}