Add godot-matrix to the list of SDKs

supporting-docs/projects/2017-09-13-godot-matrix.md

@@ -0,0 +1,13 @@
+---
+layout: project
+title: godot-matrix
+categories: projects sdk
+# valid categories are client, server, as (application service), sdk (client sdk), and other
+description: Godot Engine module for Matrix client
+author: vurpo
+maturity: Alpha
+---
+
+# {{ page.title }}
+Module for [Godot Engine](https://godotengine.org) that lets you easily integrate a Matrix client into a game developed using Godot (for example for in-game chat, matchmaking, lobbies, or something else entirely). [Source](https://gitlab.com/vurpo/godot-matrix)
+