upgrading_2.X_to_3.0.md

Upgrading from 2.X to 3.0

The biggest change in 3.0 is the requirement for PHP 8. There are some minor type-hint related changes, however the main APIs are the same as 2.X.

In addition note the following:

• somnambulist/domain has been updated and is now namespaced Somnambulist\Components\Domain
• somnambulist/collection has been updated and is now namespaced Somnambulist\Components\Collection