Added a readme file.

README.md

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+Boost.MPL
+==========
+
+Boost.MPL, part of collection of the [Boost C++ Libraries](http://github.com/boostorg), is a library for meta-programming.
+
+### Directories
+
+* **doc** - Documentation of the components
+* **include** - Interface headers
+* **test** - Unit tests
+
+The core components of the library are in the Boost.MPL.Core sublibrary, which resides in the **core** subdirectory.
+
+### More information
+
+* [Documentation](http://www.boost.org/doc/libs/release/libs/mpl/doc/index.html)
+
+### License
+
+Distributed under the [Boost Software License, Version 1.0](http://boost.org/LICENSE_1_0.txt).