Properly init in-memory usage when restoring the state (#610)

* Save useToken between config changes

* Move the DisposalEffect to set in-memory state to a higher up composable

When restoring the state after the activity got killed, the NavController would immidiately launch the previous destination
even before running the DisposableEffect. Moving the effect up fixes this timing issue.

Clean up the README.md file to focus on 3rd party devs (#606)

* Extract SDK's technical details from the readme.md

* Add Features/Installation/Documentation sections to the README.md

* Replace groovy examples with Kotlin script syntax

Release 2.3.1

Release 2.3.0

Release 2.3.0-rc2

Release 2.3.0-rc1

Release 2.2.0

Merge pull request #439 from Automattic/hamorillo/2.1.0-preparation

Prepare 2.1.0 release

Merge pull request #434 from Automattic/hamorillo/2.0.1-prepare-release

Increase version number to 2.0.1 and generate documentation