README, add note about reading readmes

Author: addshore

README.md

@@ -2,6 +2,8 @@
 
 This repo contains images needed to setup Wikibase and a query service using Docker.
 
+Each image contained within this repo has its own README (linked below).
+
 ### Issue tracking
 
 We use [Phabricator to track
@@ -21,4 +23,4 @@ Image name               | Description   | README
 
 This repo contains an EXAMPLE docker compose setup for Wikibase.
 
-[README](https://github.com/wmde/wikibase-docker/blob/master/README-compose.md)
+[README](https://github.com/wmde/wikibase-docker/blob/master/README-compose.md)