Summary:
As a starting point for `Eden.project.toml`, I figured I would pick the
working set I have been using when working on Eden in Nuclide:
```
fbcode/common
fbcode/eden
fbcode/folly
fbcode/scm
fbcode/watchman
```
Let's get this in as a starting point so the file gets picked up by Nuclide's
sitevar for `*.project.toml` files in fbsource.
Reviewed By: matthewwithanm
Differential Revision: D7716775
fbshipit-source-id: 8f760ee13c40830b5a55852b27bb7c2f825e83ff
