Rename this repository

[gholms]

When I browsed the hphelion page on GitHub and ran across a repository called "tools" I expected to find tools that work with things like Helion OpenStack or Helion Eucalyptus. It instead contains documentation build scripts. Moreover, its name is even less useful outside the context of this specific location -- if I were to clone it I would wind up with a meaningless "gholms/tools" repository. A more descriptive name, such as "helion-doc-tools", would solve both of these problems.