redis: add readme

db.redis/README.md

@@ -0,0 +1,11 @@
+## db.redis
+
+#### Role arguments:
+
+```yaml
+redis:
+  # a string designating the port to bind
+  port: "6379"
+  # (optional) a string overriding the default docker image
+  image: "redis:buster"
+```