statsd docs (Issue #2002)

[salaxander]

This is the start of documentation for statsd (issue #2002). Happy to add more detail if needed, but this should be enough to get people off the ground with it :)

[googlebot]

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[dashpole]

/ok-to-test

[salaxander]

Signed the CLA! :)

[googlebot]

We found a Contributor License Agreement for you (the sender of this pull request), but were unable to find agreements for all the commit author(s) or Co-authors. If you authored these, maybe you used a different email address in the git commits than was used to sign the CLA (login here to double check)? If these were authored by someone else, then they will need to sign a CLA as well, and confirm that they're okay with these being contributed to Google.
In order to pass this check, please resolve this problem and have the pull request author add another comment and the bot will run again. If the bot doesn't comment, it means it doesn't think anything has changed.

[salaxander]

Comment for another CLA check!

[dashpole]

make sure you follow this: https://help.github.com/articles/setting-your-commit-email-address-on-github/. From the fact that I dont see your icon on the commits above, this is probably what you are missing

[salaxander]

Comment for another CLA check!

[googlebot]

CLAs look good, thanks!

[salaxander]

@dashpole - Thanks for the guidance on that! Turns out I was missing an alternate email on my Google and GitHub account

[dashpole]

lgtm