git: openjdk/skara: Adding project explanation

[duke]

Changeset: 20c3f55c
Author:    Marcus Hirt <hirt at openjdk.org>
Committer: Erik Helin <ehelin at openjdk.org>
Date:      2019-08-26 06:13:23 +0000
URL:       https://github.com/openjdk/skara/commit/20c3f55c

Adding project explanation

Co-authored-by: Erik Duveblad <ehelin at openjdk.java.net>
Reviewed-by: ehelin

! README.md