Add this implementation to msgpack.org

[Symbolics]

According to the msgpack website instructions, this involves:

1. Add the keyword msgpack.org[ProjctName] to description of your github repository. ProjectName is typically name of a programming language such as ruby
2. Add one of following files to the root directory of your github repository:

• msgpack.org.md
• README.md
• README.markdown
• README.rdoc
• README.rst
• README

3. Wait a moment. The crawler visits your github repository every hour.

It also suggest naming the project msgpack-lisp.