What's Changed
* data.size and data.columns in schema by perolavsvendsen in https://github.com/equinor/fmu-dataio/pull/321
* Brush-up the README by perolavsvendsen in https://github.com/equinor/fmu-dataio/pull/323
* Add fmu_restart metadata on iteration level by alifbe in https://github.com/equinor/fmu-dataio/pull/314
* test py37, 38, 39, 310 and 311 by perolavsvendsen in https://github.com/equinor/fmu-dataio/pull/322
* Allow no iteration.id and put logic on iteration.name by perolavsvendsen in https://github.com/equinor/fmu-dataio/pull/306
**Full Changelog**: https://github.com/equinor/fmu-dataio/compare/1.5.3...1.6.0