Docs: Update federation.md

[lleadbet]

Small fast-follow on #2115 PR; missed adding the version to the code snippet below.

I have:

• Added tests covering the bug / feature (see testing)
• Updated any relevant documentation (see docs)

[coveralls]

Coverage remained the same at 74.735% when pulling 0c41c7e on lleadbet:patch-1 into 8f0631d on 99designs:master.

[StevenACoffman]

I actually wanted to get the release out before updating the documentation, since by default, prior to that the main site's example doc would otherwise have failed to work.