Bug: Docs refer to nonexistent tool rosdistro_reformat

[Ryan]

In the contributing guidelines, it refers to rosdistro_reformat which doesn't exist. Can you update the docs with the preferred formatting tool to run on a contribution?

Reference:

rosdistro/CONTRIBUTING.md

Line 319 in 58017cb

 There is a tool ``rosdistro_reformat`` which will fix most formatting errors such as alphabetization and correct formatting.