Add example config (Fix #48)

config.lua.example

@@ -0,0 +1,13 @@
+return {
+	port = 7575,
+	sites_dir = "./sites",
+	trusted_servers = { -- IPs of servers that are allowed to send Gitea webhooks
+	},
+	matrix = {
+		homeserver = "https://matrix.org",
+		username = "bot:matrix.org",
+		password = "Sup@rS3cure",
+		room_id = "", -- Room ID can be found under "room settings" in most clients
+		disabled = false
+	}
+}