autoversion.create_tags docs inconsistent with defaults

[athompson-r7]

Documentation and code defaults for autoversion.create_tags are inconsistent. I'm not sure which is right.

https://github.com/rapid7/builderator/blob/master/lib/builderator/config/defaults.rb#L16
and
https://github.com/rapid7/builderator/blob/master/docs/versioning.md#configuration

[Erran Carey]

@athompson-r7 looks like @jmanero-r7 updated the default in fd07254 without adjusting the documentation.