Move Usage section to a separate file

doc/index.rst

@@ -2,25 +2,9 @@
 C++ Format
 ##########
 
-*****
-Usage
-*****
-
-To use the C++ Format library, add ``format.h`` and ``format.cc`` from
-a `release archive <https://github.com/cppformat/cppformat/releases/latest>`_
-or the `Git repository <https://github.com/cppformat/cppformat>`_ to your project.
-
-If you are using Visual C++ with precompiled headers, you might need to add
-the line
-
-::
-
-   #include "stdafx.h"
-
-before other includes in ``format.cc``.
-
 .. toctree::
    :maxdepth: 2
 
+   usage
    reference
    syntax

doc/usage.rst

+.. highlight:: c++
+
+*****
+Usage
+*****
+
+To use the C++ Format library, add ``format.h`` and ``format.cc`` from
+a `release archive <https://github.com/cppformat/cppformat/releases/latest>`_
+or the `Git repository <https://github.com/cppformat/cppformat>`_ to your project.
+
+If you are using Visual C++ with precompiled headers, you might need to add
+the line
+
+::
+
+   #include "stdafx.h"
+
+before other includes in ``format.cc``.