document our project governance model (#2675)

.github/GOVERNANCE.md

@@ -0,0 +1,30 @@
+# i3 project governance
+
+## Overview
+
+The i3 project uses a governance model commonly described as Benevolent
+Dictator For Life (BDFL). This document outlines our understanding of what this
+means.
+
+## Roles
+
+* user: anyone who interacts with the i3 project
+* core contributor: a handful of people who have contributed significantly to
+  the project by any means (issue triage, support, documentation, code, etc.).
+  Core contributors are recognizable via GitHub’s “Member” badge.
+* BDFL: a single individual who makes decisions when consensus cannot be
+  reached. i3’s current BDFL is [@stapelberg](https://github.com/stapelberg).
+
+## Decision making process
+
+In general, we try to reach consensus in discussions. In case consensus cannot
+be reached, the BDFL makes a decision.
+
+For feature requests and code contributions specifically, the values with which
+we consider them can be found on the bottom of https://i3wm.org/. These values
+are not set in stone and are to be treated as guiding principles, not absolute
+rules that must be followed in every case.
+
+## Contribution process
+
+Please see [CONTRIBUTING](CONTRIBUTING.md).