Upgrade guide for users 0.15 and below with all removals and deprecations

As a reference https://docs.pola.rs/releases/upgrade/1/#change-data-orientation-inference-logic-for-dataframe-construction

It should be in both formats: Guide on the site and the Migration Notebook like https://github.com/Kotlin/dataframe/tree/master/examples/notebooks/feature_overviews/0.15 (or two notebooks (one in 0.15 other in Beta-2) to compare