Fix hard coded max width in Sphinx rtd theme

* improves document reading experience
      on wider monitors
    * added _templates/layout.html to set
      max width to none

Related-To: #496
Closes: #496
Change-Id: I1f2fc0a958cf9f6526ca314142fbcba34b5ef5c7

docs/source/_templates/layout.html

@@ -0,0 +1,8 @@
+{% extends "!layout.html" %}
+  {% block footer %} {{ super() }}
+
+  <style>
+         .wy-nav-content { max-width: none; }
+  </style>
+
+{% endblock %}