test on gitlab CI

.gitlab-ci.yml

@@ -0,0 +1,9 @@
+---
+
+stages:
+  - check
+
+Check config:
+  stage: check
+  scripts:
+    i3 -C config

README.md

@@ -1,2 +1,12 @@
 # i3
-i3 configuration
+
+Basic i3 configuration
+* scripts in bin/
+* temporary files in run/ (should not be pushed)
+* env file for various specific variables:
+
+```
+PRIMARY_OUTPUT=HDMI-1
+SECONDARY_OUTPUT=HDMI-2
+SECONDARY_OUTPUT_POSITION=--left-of
+```