add a README

README.md

+## unpunch - a configurable matrix sequencer for Pd
+
+This is a matrix sequencer abstraction. Some people also refer to
+this type as piano-roll sequencer, where notes are arranged on a grid
+where the vertical axis represents the pitch and the horizontal axis
+represents the time.
+
+### Dependencies
+
+ * A somewhat recent Pd version
+
+### Author
+
+ * Roman Haefeli
+
+### Licences
+
+Please check LICENSE.txt