Layed out the structure of documentation for installation, changelog,

known_issues and release notes.

docs/introduction/changes/index.rst

+Changes
+=======

docs/introduction/index.rst

@@ -4,8 +4,8 @@ Introduction
 .. toctree::
    :maxdepth: 1
 
-   install
-   release_notes
-   changes
-   known_issues
+   install/index
+   release_notes/index
+   changes/index
+   known_issues/index
 

docs/introduction/install/index.rst

+Installing MOOSE
+===============

docs/introduction/known_issues/index.rst

+Known Issues and bugs 
+===================

docs/introduction/release_notes/index.rst

+Release Notes
+============