Update readme state-file path to match actual default

[tmonk42]

If you follow the README and set state-dir path to "/var/lib/sensu" bad things happen. The actual default is "/var/lib/sensu/sensu-backend" and we should reflect that in the README. Signed-off-by: Nathan Haneysmith nathan@chef.io

Pull Request Checklist

Is this in reference to an existing issue?

General

• [ ] Update Changelog following the conventions laid out here

• [x] Update README with any necessary configuration snippets

• [ ] Cookstyle (rubocop) passes No (but not because of README)

• [ ] Foodcritic passes (foodcritic is depreciated)

• [ ] Rspec (unit tests) passes

• [ ] Inspec (integration tests) passes

New Features

• [ ] Added a Testing Artifact as either an automated test or a manual artifact on the PR.

• [x] Adedd documentation for it to the README.md

Purpose

Just updating documentation to reflect proper default value.

Known Compatibility Issues

[webframp]

Thanks @tmonk42 great to see you around and contributing!

[majormoses]

@webframp can you write up a changelog entry before releasing it as a major?

[webframp]

Yea @majormoses I’ll do that, no problem