Fix docker compose (#926)

Co-authored-by: Jesse Wright <[email protected]>

Author: matthieubosquet

docker-compose.yml

@@ -1,7 +1,8 @@
-jekyll:
-  image: jekyll/jekyll
-  command: jekyll serve --watch --incremental
-  ports:
-    - 4000:4000
-  volumes:
-    - .:/srv/jekyll
+services:
+  jekyll:
+    image: jekyll/jekyll
+    command: jekyll serve --watch --incremental
+    ports:
+      - 4000:4000
+    volumes:
+      - .:/srv/jekyll