Add core maintainers (#38)

governance/core-maintainers.md

@@ -0,0 +1,21 @@
+# Core Maintainers Group
+
+- [Jan Gazda](https://github.com/1oglop1)
+- [Aaron Kao](https://github.com/aaronkao)
+- [Andreas Harter](https://github.com/aharter)
+- [Derek Beattie](https://github.com/dbeattie71)
+- [Daniel Hagen](https://github.com/dbhagen)
+- [Engin Diri](https://github.com/dirien)
+- [Geoffrey Huntley](https://github.com/ghuntley)
+- [Henrik Sjööh](https://github.com/henriiik)
+- [Jonathan Gautheron](https://github.com/jgautheron)
+- [Marcel Arns](https://github.com/marns93)
+- [Daniel Mühlbachler-Pietrzykowski](https://github.com/muhlba91)
+- [Piers Karsenbarg](https://github.com/pierskarsenbarg)
+- [David Flanagan](https://github.com/rawkode)
+- [Richard Shade](https://github.com/rshade)
+- [Ringo De Smet](https://github.com/ringods)
+- [Weston Schmidt](https://github.com/schmidtw)
+- [Simen A. W. Olsen](https://github.com/simenandre)
+- [Thomas Meckel](https://github.com/tmeckel)
+- [Ivan Sabelnikov](https://github.com/vavsab)